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[pf3gnuchains/pf3gnuchains3x.git] / tk / generic / tkSelect.c
diff --git a/tk/generic/tkSelect.c b/tk/generic/tkSelect.c
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+/* 
+ * tkSelect.c --
+ *
+ *     This file manages the selection for the Tk toolkit,
+ *     translating between the standard X ICCCM conventions
+ *     and Tcl commands.
+ *
+ * Copyright (c) 1990-1993 The Regents of the University of California.
+ * Copyright (c) 1994-1997 Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * RCS: @(#) $Id$
+ */
+
+#include "tkInt.h"
+#include "tkSelect.h"
+
+/*
+ * When a selection handler is set up by invoking "selection handle",
+ * one of the following data structures is set up to hold information
+ * about the command to invoke and its interpreter.
+ */
+
+typedef struct {
+    Tcl_Interp *interp;                /* Interpreter in which to invoke command. */
+    int cmdLength;             /* # of non-NULL bytes in command. */
+    int charOffset;            /* The offset of the next char to retrieve. */
+    int byteOffset;            /* The expected byte offset of the next
+                                * chunk. */
+    char buffer[TCL_UTF_MAX];  /* A buffer to hold part of a UTF character
+                                * that is split across chunks.*/
+    char command[4];           /* Command to invoke.  Actual space is
+                                * allocated as large as necessary.  This
+                                * must be the last entry in the structure. */
+} CommandInfo;
+
+/*
+ * When selection ownership is claimed with the "selection own" Tcl command,
+ * one of the following structures is created to record the Tcl command
+ * to be executed when the selection is lost again.
+ */
+
+typedef struct LostCommand {
+    Tcl_Interp *interp;                /* Interpreter in which to invoke command. */
+    char command[4];           /* Command to invoke.  Actual space is
+                                * allocated as large as necessary.  This
+                                * must be the last entry in the structure. */
+} LostCommand;
+
+/*
+ * The structure below is used to keep each thread's pending list
+ * separate.
+ */
+
+typedef struct ThreadSpecificData {
+    TkSelInProgress *pendingPtr;
+                               /* Topmost search in progress, or
+                                * NULL if none. */
+} ThreadSpecificData;
+static Tcl_ThreadDataKey dataKey;
+
+/*
+ * Forward declarations for procedures defined in this file:
+ */
+
+static int             HandleTclCommand _ANSI_ARGS_((ClientData clientData,
+                           int offset, char *buffer, int maxBytes));
+static void            LostSelection _ANSI_ARGS_((ClientData clientData));
+static int             SelGetProc _ANSI_ARGS_((ClientData clientData,
+                           Tcl_Interp *interp, char *portion));
+\f
+/*
+ *--------------------------------------------------------------
+ *
+ * Tk_CreateSelHandler --
+ *
+ *     This procedure is called to register a procedure
+ *     as the handler for selection requests of a particular
+ *     target type on a particular window for a particular
+ *     selection.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     In the future, whenever the selection is in tkwin's
+ *     window and someone requests the selection in the
+ *     form given by target, proc will be invoked to provide
+ *     part or all of the selection in the given form.  If
+ *     there was already a handler declared for the given
+ *     window, target and selection type, then it is replaced.
+ *     Proc should have the following form:
+ *
+ *     int
+ *     proc(clientData, offset, buffer, maxBytes)
+ *         ClientData clientData;
+ *         int offset;
+ *         char *buffer;
+ *         int maxBytes;
+ *     {
+ *     }
+ *
+ *     The clientData argument to proc will be the same as
+ *     the clientData argument to this procedure.  The offset
+ *     argument indicates which portion of the selection to
+ *     return:  skip the first offset bytes.  Buffer is a
+ *     pointer to an area in which to place the converted
+ *     selection, and maxBytes gives the number of bytes
+ *     available at buffer.  Proc should place the selection
+ *     in buffer as a string, and return a count of the number
+ *     of bytes of selection actually placed in buffer (not
+ *     including the terminating NULL character).  If the
+ *     return value equals maxBytes, this is a sign that there
+ *     is probably still more selection information available.
+ *
+ *--------------------------------------------------------------
+ */
+
+void
+Tk_CreateSelHandler(tkwin, selection, target, proc, clientData, format)
+    Tk_Window tkwin;           /* Token for window. */
+    Atom selection;            /* Selection to be handled. */
+    Atom target;               /* The kind of selection conversions
+                                * that can be handled by proc,
+                                * e.g. TARGETS or STRING. */
+    Tk_SelectionProc *proc;    /* Procedure to invoke to convert
+                                * selection to type "target". */
+    ClientData clientData;     /* Value to pass to proc. */
+    Atom format;               /* Format in which the selection
+                                * information should be returned to
+                                * the requestor. XA_STRING is best by
+                                * far, but anything listed in the ICCCM
+                                * will be tolerated (blech). */
+{
+    register TkSelHandler *selPtr;
+    TkWindow *winPtr = (TkWindow *) tkwin;
+
+    if (winPtr->dispPtr->multipleAtom == None) {
+       TkSelInit(tkwin);
+    }
+
+    /*
+     * See if there's already a handler for this target and selection on
+     * this window.  If so, re-use it.  If not, create a new one.
+     */
+
+    for (selPtr = winPtr->selHandlerList; ; selPtr = selPtr->nextPtr) {
+       if (selPtr == NULL) {
+           selPtr = (TkSelHandler *) ckalloc(sizeof(TkSelHandler));
+           selPtr->nextPtr = winPtr->selHandlerList;
+           winPtr->selHandlerList = selPtr;
+           break;
+       }
+       if ((selPtr->selection == selection) && (selPtr->target == target)) {
+
+           /*
+            * Special case:  when replacing handler created by
+            * "selection handle", free up memory.  Should there be a
+            * callback to allow other clients to do this too?
+            */
+
+           if (selPtr->proc == HandleTclCommand) {
+               ckfree((char *) selPtr->clientData);
+           }
+           break;
+       }
+    }
+    selPtr->selection = selection;
+    selPtr->target = target;
+    selPtr->format = format;
+    selPtr->proc = proc;
+    selPtr->clientData = clientData;
+    if (format == XA_STRING) {
+       selPtr->size = 8;
+    } else {
+       selPtr->size = 32;
+    }
+
+    if ((target == XA_STRING) && (winPtr->dispPtr->utf8Atom != (Atom) NULL)) {
+       /*
+        * If the user asked for a STRING handler and we understand
+        * UTF8_STRING, we implicitly create a UTF8_STRING handler for them.
+        */
+
+       target = winPtr->dispPtr->utf8Atom;
+       for (selPtr = winPtr->selHandlerList; ;
+            selPtr = selPtr->nextPtr) {
+           if (selPtr == NULL) {
+               selPtr = (TkSelHandler *) ckalloc(sizeof(TkSelHandler));
+               selPtr->nextPtr = winPtr->selHandlerList;
+               winPtr->selHandlerList = selPtr;
+               selPtr->selection = selection;
+               selPtr->target = target;
+               selPtr->format = target; /* We want UTF8_STRING format */
+               selPtr->proc = proc;
+               if (selPtr->proc == HandleTclCommand) {
+                   /*
+                    * The clientData is selection controlled memory, so
+                    * we should make a copy for this selPtr.
+                    */
+                   selPtr->clientData =
+                       (ClientData) ckalloc(sizeof(clientData));
+                   memcpy(selPtr->clientData, clientData, sizeof(clientData));
+               } else {
+                   selPtr->clientData = clientData;
+               }
+               selPtr->size = 8;
+               break;
+           }
+           if ((selPtr->selection == selection)
+                   && (selPtr->target == target)) {
+               /*
+                * Looks like we had a utf-8 target already.  Leave it alone.
+                */
+
+               break;
+           }
+       }
+    }
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tk_DeleteSelHandler --
+ *
+ *     Remove the selection handler for a given window, target, and
+ *     selection, if it exists.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     The selection handler for tkwin and target is removed.  If there
+ *     is no such handler then nothing happens.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tk_DeleteSelHandler(tkwin, selection, target)
+    Tk_Window tkwin;                   /* Token for window. */
+    Atom selection;                    /* The selection whose handler
+                                        * is to be removed. */
+    Atom target;                       /* The target whose selection
+                                        * handler is to be removed. */
+{
+    TkWindow *winPtr = (TkWindow *) tkwin;
+    register TkSelHandler *selPtr, *prevPtr;
+    register TkSelInProgress *ipPtr;
+    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
+            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
+
+    /*
+     * Find the selection handler to be deleted, or return if it doesn't
+     * exist.
+     */ 
+
+    for (selPtr = winPtr->selHandlerList, prevPtr = NULL; ;
+           prevPtr = selPtr, selPtr = selPtr->nextPtr) {
+       if (selPtr == NULL) {
+           return;
+       }
+       if ((selPtr->selection == selection) && (selPtr->target == target)) {
+           break;
+       }
+    }
+
+    /*
+     * If ConvertSelection is processing this handler, tell it that the
+     * handler is dead.
+     */
+
+    for (ipPtr = tsdPtr->pendingPtr; ipPtr != NULL; 
+            ipPtr = ipPtr->nextPtr) {
+       if (ipPtr->selPtr == selPtr) {
+           ipPtr->selPtr = NULL;
+       }
+    }
+
+    /*
+     * Free resources associated with the handler.
+     */
+
+    if (prevPtr == NULL) {
+       winPtr->selHandlerList = selPtr->nextPtr;
+    } else {
+       prevPtr->nextPtr = selPtr->nextPtr;
+    }
+
+    if ((target == XA_STRING) && (winPtr->dispPtr->utf8Atom != (Atom) NULL)) {
+       /*
+        * If the user asked for a STRING handler and we understand
+        * UTF8_STRING, we may have implicitly created a UTF8_STRING handler
+        * for them.  Look for it and delete it as necessary.
+        */
+       TkSelHandler *utf8selPtr;
+
+       target = winPtr->dispPtr->utf8Atom;
+       for (utf8selPtr = winPtr->selHandlerList; utf8selPtr != NULL;
+            utf8selPtr = utf8selPtr->nextPtr) {
+           if ((utf8selPtr->selection == selection)
+                   && (utf8selPtr->target == target)) {
+               break;
+           }
+       }
+       if (utf8selPtr != NULL) {
+           if ((utf8selPtr->format == target)
+                   && (utf8selPtr->proc == selPtr->proc)
+                   && (utf8selPtr->size == selPtr->size)) {
+               /*
+                * This recursive call is OK, because we've
+                * changed the value of 'target'
+                */
+               Tk_DeleteSelHandler(tkwin, selection, target);
+           }
+       }
+    }
+
+    if (selPtr->proc == HandleTclCommand) {
+       /*
+        * Mark the CommandInfo as deleted and free it if we can.
+        */
+
+       ((CommandInfo*)selPtr->clientData)->interp = NULL;
+       Tcl_EventuallyFree(selPtr->clientData, TCL_DYNAMIC);
+    }
+    ckfree((char *) selPtr);
+}
+\f
+/*
+ *--------------------------------------------------------------
+ *
+ * Tk_OwnSelection --
+ *
+ *     Arrange for tkwin to become the owner of a selection.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     From now on, requests for the selection will be directed
+ *     to procedures associated with tkwin (they must have been
+ *     declared with calls to Tk_CreateSelHandler).  When the
+ *     selection is lost by this window, proc will be invoked
+ *     (see the manual entry for details).  This procedure may
+ *     invoke callbacks, including Tcl scripts, so any calling
+ *     function should be reentrant at the point where
+ *     Tk_OwnSelection is invoked.
+ *
+ *--------------------------------------------------------------
+ */
+
+void
+Tk_OwnSelection(tkwin, selection, proc, clientData)
+    Tk_Window tkwin;           /* Window to become new selection
+                                * owner. */
+    Atom selection;            /* Selection that window should own. */
+    Tk_LostSelProc *proc;      /* Procedure to call when selection
+                                * is taken away from tkwin. */
+    ClientData clientData;     /* Arbitrary one-word argument to
+                                * pass to proc. */
+{
+    register TkWindow *winPtr = (TkWindow *) tkwin;
+    TkDisplay *dispPtr = winPtr->dispPtr;
+    TkSelectionInfo *infoPtr;
+    Tk_LostSelProc *clearProc = NULL;
+    ClientData clearData = NULL;       /* Initialization needed only to
+                                        * prevent compiler warning. */
+    
+    
+    if (dispPtr->multipleAtom == None) {
+       TkSelInit(tkwin);
+    }
+    Tk_MakeWindowExist(tkwin);
+
+    /*
+     * This code is somewhat tricky.  First, we find the specified selection
+     * on the selection list.  If the previous owner is in this process, and
+     * is a different window, then we need to invoke the clearProc.  However,
+     * it's dangerous to call the clearProc right now, because it could
+     * invoke a Tcl script that wrecks the current state (e.g. it could
+     * delete the window).  To be safe, defer the call until the end of the
+     * procedure when we no longer care about the state.
+     */
+
+    for (infoPtr = dispPtr->selectionInfoPtr; infoPtr != NULL;
+           infoPtr = infoPtr->nextPtr) {
+       if (infoPtr->selection == selection) {
+           break;
+       }
+    }
+    if (infoPtr == NULL) {
+       infoPtr = (TkSelectionInfo*) ckalloc(sizeof(TkSelectionInfo));
+       infoPtr->selection = selection;
+       infoPtr->nextPtr = dispPtr->selectionInfoPtr;
+       dispPtr->selectionInfoPtr = infoPtr;
+    } else if (infoPtr->clearProc != NULL) {
+       if (infoPtr->owner != tkwin) {
+           clearProc = infoPtr->clearProc;
+           clearData = infoPtr->clearData;
+       } else if (infoPtr->clearProc == LostSelection) {
+           /*
+            * If the selection handler is one created by "selection own",
+            * be sure to free the record for it;  otherwise there will be
+            * a memory leak.
+            */
+
+           ckfree((char *) infoPtr->clearData);
+       }
+    }
+
+    infoPtr->owner = tkwin;
+    infoPtr->serial = NextRequest(winPtr->display);
+    infoPtr->clearProc = proc;
+    infoPtr->clearData = clientData;
+
+    /*
+     * Note that we are using CurrentTime, even though ICCCM recommends against
+     * this practice (the problem is that we don't necessarily have a valid
+     * time to use).  We will not be able to retrieve a useful timestamp for
+     * the TIMESTAMP target later.
+     */
+
+    infoPtr->time = CurrentTime;
+
+    /*
+     * Note that we are not checking to see if the selection claim succeeded.
+     * If the ownership does not change, then the clearProc may never be
+     * invoked, and we will return incorrect information when queried for the
+     * current selection owner.
+     */
+
+    XSetSelectionOwner(winPtr->display, infoPtr->selection, winPtr->window,
+           infoPtr->time);
+
+    /*
+     * Now that we are done, we can invoke clearProc without running into
+     * reentrancy problems.
+     */
+
+    if (clearProc != NULL) {
+       (*clearProc)(clearData);
+    }
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tk_ClearSelection --
+ *
+ *     Eliminate the specified selection on tkwin's display, if there is one.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     The specified selection is cleared, so that future requests to retrieve
+ *     it will fail until some application owns it again.  This procedure
+ *     invokes callbacks, possibly including Tcl scripts, so any calling
+ *     function should be reentrant at the point Tk_ClearSelection is invoked.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+Tk_ClearSelection(tkwin, selection)
+    Tk_Window tkwin;           /* Window that selects a display. */
+    Atom selection;            /* Selection to be cancelled. */
+{
+    register TkWindow *winPtr = (TkWindow *) tkwin;
+    TkDisplay *dispPtr = winPtr->dispPtr;
+    TkSelectionInfo *infoPtr;
+    TkSelectionInfo *prevPtr;
+    TkSelectionInfo *nextPtr;
+    Tk_LostSelProc *clearProc = NULL;
+    ClientData clearData = NULL;       /* Initialization needed only to
+                                        * prevent compiler warning. */
+
+    if (dispPtr->multipleAtom == None) {
+       TkSelInit(tkwin);
+    }
+
+    for (infoPtr = dispPtr->selectionInfoPtr, prevPtr = NULL;
+            infoPtr != NULL; infoPtr = nextPtr) {
+       nextPtr = infoPtr->nextPtr;
+       if (infoPtr->selection == selection) {
+           if (prevPtr == NULL) {
+               dispPtr->selectionInfoPtr = nextPtr;
+           } else {
+               prevPtr->nextPtr = nextPtr;
+           }
+           break;
+       }
+       prevPtr = infoPtr;
+    }
+    
+    if (infoPtr != NULL) {
+       clearProc = infoPtr->clearProc;
+       clearData = infoPtr->clearData;
+       ckfree((char *) infoPtr);
+    }
+    XSetSelectionOwner(winPtr->display, selection, None, CurrentTime);
+
+    if (clearProc != NULL) {
+       (*clearProc)(clearData);
+    }
+}
+\f
+/*
+ *--------------------------------------------------------------
+ *
+ * Tk_GetSelection --
+ *
+ *     Retrieve the value of a selection and pass it off (in
+ *     pieces, possibly) to a given procedure.
+ *
+ * Results:
+ *     The return value is a standard Tcl return value.
+ *     If an error occurs (such as no selection exists)
+ *     then an error message is left in the interp's result.
+ *
+ * Side effects:
+ *     The standard X11 protocols are used to retrieve the
+ *     selection.  When it arrives, it is passed to proc.  If
+ *     the selection is very large, it will be passed to proc
+ *     in several pieces.  Proc should have the following
+ *     structure:
+ *
+ *     int
+ *     proc(clientData, interp, portion)
+ *         ClientData clientData;
+ *         Tcl_Interp *interp;
+ *         char *portion;
+ *     {
+ *     }
+ *
+ *     The interp and clientData arguments to proc will be the
+ *     same as the corresponding arguments to Tk_GetSelection.
+ *     The portion argument points to a character string
+ *     containing part of the selection, and numBytes indicates
+ *     the length of the portion, not including the terminating
+ *     NULL character.  If the selection arrives in several pieces,
+ *     the "portion" arguments in separate calls will contain
+ *     successive parts of the selection.  Proc should normally
+ *     return TCL_OK.  If it detects an error then it should return
+ *     TCL_ERROR and leave an error message in the interp's result; the
+ *     remainder of the selection retrieval will be aborted.
+ *
+ *--------------------------------------------------------------
+ */
+
+int
+Tk_GetSelection(interp, tkwin, selection, target, proc, clientData)
+    Tcl_Interp *interp;                /* Interpreter to use for reporting
+                                * errors. */
+    Tk_Window tkwin;           /* Window on whose behalf to retrieve
+                                * the selection (determines display
+                                * from which to retrieve). */
+    Atom selection;            /* Selection to retrieve. */
+    Atom target;               /* Desired form in which selection
+                                * is to be returned. */
+    Tk_GetSelProc *proc;       /* Procedure to call to process the
+                                * selection, once it has been retrieved. */
+    ClientData clientData;     /* Arbitrary value to pass to proc. */
+{
+    TkWindow *winPtr = (TkWindow *) tkwin;
+    TkDisplay *dispPtr = winPtr->dispPtr;
+    TkSelectionInfo *infoPtr;
+    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
+            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
+
+    if (dispPtr->multipleAtom == None) {
+       TkSelInit(tkwin);
+    }
+
+    /*
+     * If the selection is owned by a window managed by this
+     * process, then call the retrieval procedure directly,
+     * rather than going through the X server (it's dangerous
+     * to go through the X server in this case because it could
+     * result in deadlock if an INCR-style selection results).
+     */
+
+    for (infoPtr = dispPtr->selectionInfoPtr; infoPtr != NULL;
+           infoPtr = infoPtr->nextPtr) {
+       if (infoPtr->selection == selection)
+           break;
+    }
+    if (infoPtr != NULL) {
+       register TkSelHandler *selPtr;
+       int offset, result, count;
+       char buffer[TK_SEL_BYTES_AT_ONCE+1];
+       TkSelInProgress ip;
+
+       for (selPtr = ((TkWindow *) infoPtr->owner)->selHandlerList;
+            selPtr != NULL; selPtr = selPtr->nextPtr) {
+           if  ((selPtr->target == target)
+                   && (selPtr->selection == selection)) {
+               break;
+           }
+       }
+       if (selPtr == NULL) {
+           Atom type;
+
+           count = TkSelDefaultSelection(infoPtr, target, buffer,
+                   TK_SEL_BYTES_AT_ONCE, &type);
+           if (count > TK_SEL_BYTES_AT_ONCE) {
+               panic("selection handler returned too many bytes");
+           }
+           if (count < 0) {
+               goto cantget;
+           }
+           buffer[count] = 0;
+           result = (*proc)(clientData, interp, buffer);
+       } else {
+           offset = 0;
+           result = TCL_OK;
+           ip.selPtr = selPtr;
+           ip.nextPtr = tsdPtr->pendingPtr;
+           tsdPtr->pendingPtr = &ip;
+           while (1) {
+               count = (selPtr->proc)(selPtr->clientData, offset, buffer,
+                       TK_SEL_BYTES_AT_ONCE);
+               if ((count < 0) || (ip.selPtr == NULL)) {
+                   tsdPtr->pendingPtr = ip.nextPtr;
+                   goto cantget;
+               }
+               if (count > TK_SEL_BYTES_AT_ONCE) {
+                   panic("selection handler returned too many bytes");
+               }
+               buffer[count] = '\0';
+               result = (*proc)(clientData, interp, buffer);
+               if ((result != TCL_OK) || (count < TK_SEL_BYTES_AT_ONCE)
+                       || (ip.selPtr == NULL)) {
+                   break;
+               }
+               offset += count;
+           }
+           tsdPtr->pendingPtr = ip.nextPtr;
+       }
+       return result;
+    }
+
+    /*
+     * The selection is owned by some other process.
+     */
+
+    return TkSelGetSelection(interp, tkwin, selection, target, proc,
+           clientData);
+
+    cantget:
+    Tcl_AppendResult(interp, Tk_GetAtomName(tkwin, selection),
+       " selection doesn't exist or form \"", Tk_GetAtomName(tkwin, target),
+       "\" not defined", (char *) NULL);
+    return TCL_ERROR;
+}
+\f
+/*
+ *--------------------------------------------------------------
+ *
+ * Tk_SelectionObjCmd --
+ *
+ *     This procedure is invoked to process the "selection" Tcl
+ *     command.  See the user documentation for details on what
+ *     it does.
+ *
+ * Results:
+ *     A standard Tcl result.
+ *
+ * Side effects:
+ *     See the user documentation.
+ *
+ *--------------------------------------------------------------
+ */
+
+int
+Tk_SelectionObjCmd(clientData, interp, objc, objv)
+    ClientData clientData;     /* Main window associated with
+                                * interpreter. */
+    Tcl_Interp *interp;                /* Current interpreter. */
+    int objc;                  /* Number of arguments. */
+    Tcl_Obj *CONST objv[];     /* Argument objects. */
+{
+    Tk_Window tkwin = (Tk_Window) clientData;
+    char *path = NULL;
+    Atom selection;
+    char *selName = NULL, *string;
+    int count, index;
+    Tcl_Obj **objs;
+    static CONST char *optionStrings[] = {
+       "clear", "get", "handle", "own", (char *) NULL
+    };
+    enum options { SELECTION_CLEAR, SELECTION_GET, SELECTION_HANDLE,
+                      SELECTION_OWN };
+    
+    if (objc < 2) {
+       Tcl_WrongNumArgs(interp, 1, objv, "option ?arg arg ...?");
+       return TCL_ERROR;
+    }
+
+    if (Tcl_GetIndexFromObj(interp, objv[1], optionStrings, "option", 0,
+           &index) != TCL_OK) {
+       return TCL_ERROR;
+    }
+
+    switch ((enum options) index) {
+       case SELECTION_CLEAR: {
+           static CONST char *clearOptionStrings[] = {
+               "-displayof", "-selection", (char *) NULL
+           };
+           enum clearOptions { CLEAR_DISPLAYOF, CLEAR_SELECTION };
+           int clearIndex;
+           
+           for (count = objc-2, objs = ((Tcl_Obj **)objv)+2; count > 0;
+                count-=2, objs+=2) {
+               string = Tcl_GetString(objs[0]);
+               if (string[0] != '-') {
+                   break;
+               }
+               if (count < 2) {
+                   Tcl_AppendResult(interp, "value for \"", string,
+                           "\" missing", (char *) NULL);
+                   return TCL_ERROR;
+               }
+
+               if (Tcl_GetIndexFromObj(interp, objs[0], clearOptionStrings,
+                       "option", 0, &clearIndex) != TCL_OK) {
+                   return TCL_ERROR;
+               }
+               switch ((enum clearOptions) clearIndex) {
+                   case CLEAR_DISPLAYOF:
+                       path = Tcl_GetString(objs[1]);
+                       break;
+                   case CLEAR_SELECTION:
+                       selName = Tcl_GetString(objs[1]);
+                       break;
+               }
+           }
+           if (count == 1) {
+               path = Tcl_GetString(objs[0]);
+           } else if (count > 1) {
+               Tcl_WrongNumArgs(interp, 2, objv, "?options?");
+               return TCL_ERROR;
+           }
+           if (path != NULL) {
+               tkwin = Tk_NameToWindow(interp, path, tkwin);
+           }
+           if (tkwin == NULL) {
+               return TCL_ERROR;
+           }
+           if (selName != NULL) {
+               selection = Tk_InternAtom(tkwin, selName);
+           } else {
+               selection = XA_PRIMARY;
+           }
+           
+           Tk_ClearSelection(tkwin, selection);
+           break;
+       }
+
+       case SELECTION_GET: {
+           Atom target;
+           char *targetName = NULL;
+           Tcl_DString selBytes;
+           int result;
+           static CONST char *getOptionStrings[] = {
+               "-displayof", "-selection", "-type", (char *) NULL
+           };
+           enum getOptions { GET_DISPLAYOF, GET_SELECTION, GET_TYPE };
+           int getIndex;
+           
+           for (count = objc-2, objs = ((Tcl_Obj **)objv)+2; count>0;
+                count-=2, objs+=2) {
+               string = Tcl_GetString(objs[0]);
+               if (string[0] != '-') {
+                   break;
+               }
+               if (count < 2) {
+                   Tcl_AppendResult(interp, "value for \"", string,
+                           "\" missing", (char *) NULL);
+                   return TCL_ERROR;
+               }
+               
+               if (Tcl_GetIndexFromObj(interp, objs[0], getOptionStrings,
+                       "option", 0, &getIndex) != TCL_OK) {
+                   return TCL_ERROR;
+               }
+
+               switch ((enum getOptions) getIndex) {
+                   case GET_DISPLAYOF:
+                       path = Tcl_GetString(objs[1]);
+                       break;
+                   case GET_SELECTION:
+                       selName = Tcl_GetString(objs[1]);
+                       break;
+                   case GET_TYPE:
+                       targetName = Tcl_GetString(objs[1]);
+                       break;
+               }
+           }
+           if (path != NULL) {
+               tkwin = Tk_NameToWindow(interp, path, tkwin);
+           }
+           if (tkwin == NULL) {
+               return TCL_ERROR;
+           }
+           if (selName != NULL) {
+               selection = Tk_InternAtom(tkwin, selName);
+           } else {
+               selection = XA_PRIMARY;
+           }
+           if (count > 1) {
+               Tcl_WrongNumArgs(interp, 2, objv, "?options?");
+               return TCL_ERROR;
+           } else if (count == 1) {
+               target = Tk_InternAtom(tkwin, Tcl_GetString(objs[0]));
+           } else if (targetName != NULL) {
+               target = Tk_InternAtom(tkwin, targetName);
+           } else {
+               target = XA_STRING;
+           }
+
+           Tcl_DStringInit(&selBytes);
+           result = Tk_GetSelection(interp, tkwin, selection, target,
+                   SelGetProc, (ClientData) &selBytes);
+           if (result == TCL_OK) {
+               Tcl_DStringResult(interp, &selBytes);
+           } else {
+               Tcl_DStringFree(&selBytes);
+           }
+           return result;
+       }
+
+       case SELECTION_HANDLE: {
+           Atom target, format;
+           char *targetName = NULL;
+           char *formatName = NULL;
+           register CommandInfo *cmdInfoPtr;
+           int cmdLength;
+           static CONST char *handleOptionStrings[] = {
+               "-format", "-selection", "-type", (char *) NULL
+           };
+           enum handleOptions { HANDLE_FORMAT, HANDLE_SELECTION,
+                                    HANDLE_TYPE };
+           int handleIndex;
+           
+           for (count = objc-2, objs = ((Tcl_Obj **)objv)+2; count > 0;
+                count-=2, objs+=2) {
+               string = Tcl_GetString(objs[0]);
+               if (string[0] != '-') {
+                   break;
+               }
+               if (count < 2) {
+                   Tcl_AppendResult(interp, "value for \"", string,
+                           "\" missing", (char *) NULL);
+                   return TCL_ERROR;
+               }
+
+               if (Tcl_GetIndexFromObj(interp, objs[0],handleOptionStrings,
+                       "option", 0, &handleIndex) != TCL_OK) {
+                   return TCL_ERROR;
+               }
+
+               switch ((enum handleOptions) handleIndex) {
+                   case HANDLE_FORMAT:
+                       formatName = Tcl_GetString(objs[1]);
+                       break;
+                   case HANDLE_SELECTION:
+                       selName = Tcl_GetString(objs[1]);
+                       break;
+                   case HANDLE_TYPE:
+                       targetName = Tcl_GetString(objs[1]);
+                       break;
+               }
+           }
+
+           if ((count < 2) || (count > 4)) {
+               Tcl_WrongNumArgs(interp, 2, objv, "?options? window command");
+               return TCL_ERROR;
+           }
+           tkwin = Tk_NameToWindow(interp, Tcl_GetString(objs[0]), tkwin);
+           if (tkwin == NULL) {
+               return TCL_ERROR;
+           }
+           if (selName != NULL) {
+               selection = Tk_InternAtom(tkwin, selName);
+           } else {
+               selection = XA_PRIMARY;
+           }
+           
+           if (count > 2) {
+               target = Tk_InternAtom(tkwin, Tcl_GetString(objs[2]));
+           } else if (targetName != NULL) {
+               target = Tk_InternAtom(tkwin, targetName);
+           } else {
+               target = XA_STRING;
+           }
+           if (count > 3) {
+               format = Tk_InternAtom(tkwin, Tcl_GetString(objs[3]));
+           } else if (formatName != NULL) {
+               format = Tk_InternAtom(tkwin, formatName);
+           } else {
+               format = XA_STRING;
+           }
+           string = Tcl_GetStringFromObj(objs[1], &cmdLength);
+           if (cmdLength == 0) {
+               Tk_DeleteSelHandler(tkwin, selection, target);
+           } else {
+               cmdInfoPtr = (CommandInfo *) ckalloc((unsigned) (
+                   sizeof(CommandInfo) - 3 + cmdLength));
+               cmdInfoPtr->interp = interp;
+               cmdInfoPtr->charOffset = 0;
+               cmdInfoPtr->byteOffset = 0;
+               cmdInfoPtr->buffer[0] = '\0';
+               cmdInfoPtr->cmdLength = cmdLength;
+               strcpy(cmdInfoPtr->command, string);
+               Tk_CreateSelHandler(tkwin, selection, target, HandleTclCommand,
+                       (ClientData) cmdInfoPtr, format);
+           }
+           return TCL_OK;
+       }
+       
+       case SELECTION_OWN: {
+           register LostCommand *lostPtr;
+           char *script = NULL;
+           int cmdLength;
+           static CONST char *ownOptionStrings[] = {
+               "-command", "-displayof", "-selection", (char *) NULL
+           };
+           enum ownOptions { OWN_COMMAND, OWN_DISPLAYOF, OWN_SELECTION };
+           int ownIndex;
+           
+           for (count = objc-2, objs = ((Tcl_Obj **)objv)+2; count > 0;
+                count-=2, objs+=2) {
+               string = Tcl_GetString(objs[0]);
+               if (string[0] != '-') {
+                   break;
+               }
+               if (count < 2) {
+                   Tcl_AppendResult(interp, "value for \"", string,
+                           "\" missing", (char *) NULL);
+                   return TCL_ERROR;
+               }
+
+               if (Tcl_GetIndexFromObj(interp, objs[0], ownOptionStrings,
+                       "option", 0, &ownIndex) != TCL_OK) {
+                   return TCL_ERROR;
+               }
+
+               switch ((enum ownOptions) ownIndex) {
+                   case OWN_COMMAND:
+                       script = Tcl_GetString(objs[1]);
+                       break;
+                   case OWN_DISPLAYOF:
+                       path = Tcl_GetString(objs[1]);
+                       break;
+                   case OWN_SELECTION:
+                       selName = Tcl_GetString(objs[1]);
+                       break;
+               }
+           }
+           
+           if (count > 2) {
+               Tcl_WrongNumArgs(interp, 2, objv, "?options? ?window?");
+               return TCL_ERROR;
+           }
+           if (selName != NULL) {
+               selection = Tk_InternAtom(tkwin, selName);
+           } else {
+               selection = XA_PRIMARY;
+           }
+           if (count == 0) {
+               TkSelectionInfo *infoPtr;
+               TkWindow *winPtr;
+               if (path != NULL) {
+                   tkwin = Tk_NameToWindow(interp, path, tkwin);
+               }
+               if (tkwin == NULL) {
+                   return TCL_ERROR;
+               }
+               winPtr = (TkWindow *)tkwin;
+               for (infoPtr = winPtr->dispPtr->selectionInfoPtr;
+                    infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
+                   if (infoPtr->selection == selection)
+                       break;
+               }
+               
+               /*
+                * Ignore the internal clipboard window.
+                */
+               
+               if ((infoPtr != NULL)
+                       && (infoPtr->owner != winPtr->dispPtr->clipWindow)) {
+                   Tcl_SetResult(interp, Tk_PathName(infoPtr->owner),
+                           TCL_STATIC);
+               }
+               return TCL_OK;
+           }
+           tkwin = Tk_NameToWindow(interp, Tcl_GetString(objs[0]), tkwin);
+           if (tkwin == NULL) {
+               return TCL_ERROR;
+           }
+           if (count == 2) {
+               script = Tcl_GetString(objs[1]);
+           }
+           if (script == NULL) {
+               Tk_OwnSelection(tkwin, selection, (Tk_LostSelProc *) NULL,
+                       (ClientData) NULL);
+               return TCL_OK;
+           }
+           cmdLength = strlen(script);
+           lostPtr = (LostCommand *) ckalloc((unsigned) (sizeof(LostCommand)
+                   -3 + cmdLength));
+           lostPtr->interp = interp;
+           strcpy(lostPtr->command, script);
+           Tk_OwnSelection(tkwin, selection, LostSelection,
+                   (ClientData) lostPtr);
+           return TCL_OK;
+       }
+    }
+    return TCL_OK;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TkSelGetInProgress --
+ *
+ *     This procedure returns a pointer to the thread-local
+ *      list of pending searches.
+ *
+ * Results:
+ *     The return value is a pointer to the first search in progress, 
+ *      or NULL if there are none. 
+ *
+ * Side effects:
+ *     None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+TkSelInProgress *
+TkSelGetInProgress _ANSI_ARGS_((void))
+{
+    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
+            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
+
+    return tsdPtr->pendingPtr;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TkSelSetInProgress --
+ *
+ *     This procedure is used to set the thread-local list of pending 
+ *      searches.  It is required because the pending list is kept
+ *      in thread local storage.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     None.
+ *
+ *----------------------------------------------------------------------
+ */
+void
+TkSelSetInProgress(pendingPtr)
+    TkSelInProgress *pendingPtr;
+{
+    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
+            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
+
+   tsdPtr->pendingPtr = pendingPtr;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TkSelDeadWindow --
+ *
+ *     This procedure is invoked just before a TkWindow is deleted.
+ *     It performs selection-related cleanup.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     Frees up memory associated with the selection.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TkSelDeadWindow(winPtr)
+    register TkWindow *winPtr; /* Window that's being deleted. */
+{
+    register TkSelHandler *selPtr;
+    register TkSelInProgress *ipPtr;
+    TkSelectionInfo *infoPtr, *prevPtr, *nextPtr;
+    ThreadSpecificData *tsdPtr = (ThreadSpecificData *) 
+            Tcl_GetThreadData(&dataKey, sizeof(ThreadSpecificData));
+
+    /*
+     * While deleting all the handlers, be careful to check whether
+     * ConvertSelection or TkSelPropProc are about to process one of the
+     * deleted handlers.
+     */
+
+    while (winPtr->selHandlerList != NULL) {
+       selPtr = winPtr->selHandlerList;
+       winPtr->selHandlerList = selPtr->nextPtr;
+       for (ipPtr = tsdPtr->pendingPtr; ipPtr != NULL; 
+                ipPtr = ipPtr->nextPtr) {
+           if (ipPtr->selPtr == selPtr) {
+               ipPtr->selPtr = NULL;
+           }
+       }
+       if (selPtr->proc == HandleTclCommand) {
+           /*
+            * Mark the CommandInfo as deleted and free it when we can.
+            */
+
+           ((CommandInfo*)selPtr->clientData)->interp = NULL;
+           Tcl_EventuallyFree(selPtr->clientData, TCL_DYNAMIC);
+       }
+       ckfree((char *) selPtr);
+    }
+
+    /*
+     * Remove selections owned by window being deleted.
+     */
+
+    for (infoPtr = winPtr->dispPtr->selectionInfoPtr, prevPtr = NULL;
+            infoPtr != NULL; infoPtr = nextPtr) {
+       nextPtr = infoPtr->nextPtr;
+       if (infoPtr->owner == (Tk_Window) winPtr) {
+           if (infoPtr->clearProc == LostSelection) {
+               ckfree((char *) infoPtr->clearData);
+           }
+           ckfree((char *) infoPtr);
+           infoPtr = prevPtr;
+           if (prevPtr == NULL) {
+               winPtr->dispPtr->selectionInfoPtr = nextPtr;
+           } else {
+               prevPtr->nextPtr = nextPtr;
+           }
+       }
+       prevPtr = infoPtr;
+    }
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TkSelInit --
+ *
+ *     Initialize selection-related information for a display.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     Selection-related information is initialized.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TkSelInit(tkwin)
+    Tk_Window tkwin;           /* Window token (used to find
+                                * display to initialize). */
+{
+    register TkDisplay *dispPtr = ((TkWindow *) tkwin)->dispPtr;
+
+    /*
+     * Fetch commonly-used atoms.
+     */
+
+    dispPtr->multipleAtom      = Tk_InternAtom(tkwin, "MULTIPLE");
+    dispPtr->incrAtom          = Tk_InternAtom(tkwin, "INCR");
+    dispPtr->targetsAtom       = Tk_InternAtom(tkwin, "TARGETS");
+    dispPtr->timestampAtom     = Tk_InternAtom(tkwin, "TIMESTAMP");
+    dispPtr->textAtom          = Tk_InternAtom(tkwin, "TEXT");
+    dispPtr->compoundTextAtom  = Tk_InternAtom(tkwin, "COMPOUND_TEXT");
+    dispPtr->applicationAtom   = Tk_InternAtom(tkwin, "TK_APPLICATION");
+    dispPtr->windowAtom                = Tk_InternAtom(tkwin, "TK_WINDOW");
+    dispPtr->clipboardAtom     = Tk_InternAtom(tkwin, "CLIPBOARD");
+
+    /*
+     * Using UTF8_STRING instead of the XA_UTF8_STRING macro allows us
+     * to support older X servers that didn't have UTF8_STRING yet.
+     * This is necessary on Unix systems.
+     * For more information, see:
+     *    http://www.cl.cam.ac.uk/~mgk25/unicode.html#x11
+     */
+
+#if !(defined(__WIN32__) || defined(MAC_TCL) || defined(MAC_OSX_TK))
+    dispPtr->utf8Atom          = Tk_InternAtom(tkwin, "UTF8_STRING");
+#else
+    dispPtr->utf8Atom          = (Atom) NULL;
+#endif
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TkSelClearSelection --
+ *
+ *     This procedure is invoked to process a SelectionClear event.
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     Invokes the clear procedure for the window which lost the
+ *     selection.
+ *
+ *----------------------------------------------------------------------
+ */
+
+void
+TkSelClearSelection(tkwin, eventPtr)
+    Tk_Window tkwin;           /* Window for which event was targeted. */
+    register XEvent *eventPtr; /* X SelectionClear event. */
+{
+    register TkWindow *winPtr = (TkWindow *) tkwin;
+    TkDisplay *dispPtr = winPtr->dispPtr;
+    TkSelectionInfo *infoPtr;
+    TkSelectionInfo *prevPtr;
+
+    /*
+     * Invoke clear procedure for window that just lost the selection.  This
+     * code is a bit tricky, because any callbacks due to selection changes
+     * between windows managed by the process have already been made.  Thus,
+     * ignore the event unless it refers to the window that's currently the
+     * selection owner and the event was generated after the server saw the
+     * SetSelectionOwner request.
+     */
+
+    for (infoPtr = dispPtr->selectionInfoPtr, prevPtr = NULL;
+        infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
+       if (infoPtr->selection == eventPtr->xselectionclear.selection) {
+           break;
+       }
+       prevPtr = infoPtr;
+    }
+
+    if (infoPtr != NULL && (infoPtr->owner == tkwin)
+           && (eventPtr->xselectionclear.serial >= (unsigned) infoPtr->serial)) {
+       if (prevPtr == NULL) {
+           dispPtr->selectionInfoPtr = infoPtr->nextPtr;
+       } else {
+           prevPtr->nextPtr = infoPtr->nextPtr;
+       }
+
+       /*
+        * Because of reentrancy problems, calling clearProc must be done
+        * after the infoPtr has been removed from the selectionInfoPtr
+        * list (clearProc could modify the list, e.g. by creating
+        * a new selection).
+        */
+
+       if (infoPtr->clearProc != NULL) {
+           (*infoPtr->clearProc)(infoPtr->clearData);
+       }
+       ckfree((char *) infoPtr);
+    }
+}
+\f
+/*
+ *--------------------------------------------------------------
+ *
+ * SelGetProc --
+ *
+ *     This procedure is invoked to process pieces of the selection
+ *     as they arrive during "selection get" commands.
+ *
+ * Results:
+ *     Always returns TCL_OK.
+ *
+ * Side effects:
+ *     Bytes get appended to the dynamic string pointed to by the
+ *     clientData argument.
+ *
+ *--------------------------------------------------------------
+ */
+
+       /* ARGSUSED */
+static int
+SelGetProc(clientData, interp, portion)
+    ClientData clientData;     /* Dynamic string holding partially
+                                * assembled selection. */
+    Tcl_Interp *interp;                /* Interpreter used for error
+                                * reporting (not used). */
+    char *portion;             /* New information to be appended. */
+{
+    Tcl_DStringAppend((Tcl_DString *) clientData, portion, -1);
+    return TCL_OK;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * HandleTclCommand --
+ *
+ *     This procedure acts as selection handler for handlers created
+ *     by the "selection handle" command.  It invokes a Tcl command to
+ *     retrieve the selection.
+ *
+ * Results:
+ *     The return value is a count of the number of bytes actually
+ *     stored at buffer, or -1 if an error occurs while executing
+ *     the Tcl command to retrieve the selection.
+ *
+ * Side effects:
+ *     None except for things done by the Tcl command.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+HandleTclCommand(clientData, offset, buffer, maxBytes)
+    ClientData clientData;     /* Information about command to execute. */
+    int offset;                        /* Return selection bytes starting at this
+                                * offset. */
+    char *buffer;              /* Place to store converted selection. */
+    int maxBytes;              /* Maximum # of bytes to store at buffer. */
+{
+    CommandInfo *cmdInfoPtr = (CommandInfo *) clientData;
+    int spaceNeeded, length;
+#define MAX_STATIC_SIZE 100
+    char staticSpace[MAX_STATIC_SIZE];
+    char *command, *string;
+    Tcl_Interp *interp = cmdInfoPtr->interp;
+    Tcl_DString oldResult;
+    Tcl_Obj *objPtr;
+    int extraBytes, charOffset, count, numChars;
+    CONST char *p;
+
+    /*
+     * We must also protect the interpreter and the command from being
+     * deleted too soon.
+     */
+
+    Tcl_Preserve(clientData);
+    Tcl_Preserve((ClientData) interp);
+
+    /*
+     * Compute the proper byte offset in the case where the last chunk
+     * split a character.
+     */
+
+    if (offset == cmdInfoPtr->byteOffset) {
+       charOffset = cmdInfoPtr->charOffset;
+       extraBytes = strlen(cmdInfoPtr->buffer);
+       if (extraBytes > 0) {
+           strcpy(buffer, cmdInfoPtr->buffer);
+           maxBytes -= extraBytes;
+           buffer += extraBytes;
+       }
+    } else {
+       cmdInfoPtr->byteOffset = 0;
+       cmdInfoPtr->charOffset = 0;
+       extraBytes = 0;
+       charOffset = 0;
+    }
+
+    /*
+     * First, generate a command by taking the command string
+     * and appending the offset and maximum # of bytes.
+     */
+
+    spaceNeeded = cmdInfoPtr->cmdLength + 30;
+    if (spaceNeeded < MAX_STATIC_SIZE) {
+       command = staticSpace;
+    } else {
+       command = (char *) ckalloc((unsigned) spaceNeeded);
+    }
+    sprintf(command, "%s %d %d", cmdInfoPtr->command, charOffset, maxBytes);
+
+    /*
+     * Execute the command.  Be sure to restore the state of the
+     * interpreter after executing the command.
+     */
+
+    Tcl_DStringInit(&oldResult);
+    Tcl_DStringGetResult(interp, &oldResult);
+    if (TkCopyAndGlobalEval(interp, command) == TCL_OK) {
+       objPtr = Tcl_GetObjResult(interp);
+       string = Tcl_GetStringFromObj(objPtr, &length);
+       count = (length > maxBytes) ? maxBytes : length;
+       memcpy((VOID *) buffer, (VOID *) string, (size_t) count);
+       buffer[count] = '\0';
+
+       /*
+        * Update the partial character information for the next
+        * retrieval if the command has not been deleted.
+        */
+
+       if (cmdInfoPtr->interp != NULL) {
+           if (length <= maxBytes) {
+               cmdInfoPtr->charOffset += Tcl_NumUtfChars(string, -1);
+               cmdInfoPtr->buffer[0] = '\0';
+           } else {
+               p = string;
+               string += count;
+               numChars = 0;
+               while (p < string) {
+                   p = Tcl_UtfNext(p);
+                   numChars++;
+               }
+               cmdInfoPtr->charOffset += numChars;
+               length = p - string;
+               if (length > 0) {
+                   strncpy(cmdInfoPtr->buffer, string, (size_t) length);
+               }
+               cmdInfoPtr->buffer[length] = '\0';
+           }           
+           cmdInfoPtr->byteOffset += count + extraBytes;
+       }
+       count += extraBytes;
+    } else {
+       count = -1;
+    }
+    Tcl_DStringResult(interp, &oldResult);
+
+    if (command != staticSpace) {
+       ckfree(command);
+    }
+
+
+    Tcl_Release(clientData);
+    Tcl_Release((ClientData) interp);
+    return count;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * TkSelDefaultSelection --
+ *
+ *     This procedure is called to generate selection information
+ *     for a few standard targets such as TIMESTAMP and TARGETS.
+ *     It is invoked only if no handler has been declared by the
+ *     application.
+ *
+ * Results:
+ *     If "target" is a standard target understood by this procedure,
+ *     the selection is converted to that form and stored as a
+ *     character string in buffer.  The type of the selection (e.g.
+ *     STRING or ATOM) is stored in *typePtr, and the return value is
+ *     a count of the # of non-NULL bytes at buffer.  If the target
+ *     wasn't understood, or if there isn't enough space at buffer
+ *     to hold the entire selection (no INCR-mode transfers for this
+ *     stuff!), then -1 is returned.
+ *
+ * Side effects:
+ *     None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+int
+TkSelDefaultSelection(infoPtr, target, buffer, maxBytes, typePtr)
+    TkSelectionInfo *infoPtr;  /* Info about selection being retrieved. */
+    Atom target;               /* Desired form of selection. */
+    char *buffer;              /* Place to put selection characters. */
+    int maxBytes;              /* Maximum # of bytes to store at buffer. */
+    Atom *typePtr;             /* Store here the type of the selection,
+                                * for use in converting to proper X format. */
+{
+    register TkWindow *winPtr = (TkWindow *) infoPtr->owner;
+    TkDisplay *dispPtr = winPtr->dispPtr;
+
+    if (target == dispPtr->timestampAtom) {
+       if (maxBytes < 20) {
+           return -1;
+       }
+       sprintf(buffer, "0x%x", (unsigned int) infoPtr->time);
+       *typePtr = XA_INTEGER;
+       return strlen(buffer);
+    }
+
+    if (target == dispPtr->targetsAtom) {
+       register TkSelHandler *selPtr;
+       CONST char *atomString;
+       int length, atomLength;
+
+       if (maxBytes < 50) {
+           return -1;
+       }
+       strcpy(buffer, "MULTIPLE TARGETS TIMESTAMP TK_APPLICATION TK_WINDOW");
+       length = strlen(buffer);
+       for (selPtr = winPtr->selHandlerList; selPtr != NULL;
+               selPtr = selPtr->nextPtr) {
+           if ((selPtr->selection == infoPtr->selection)
+                   && (selPtr->target != dispPtr->applicationAtom)
+                   && (selPtr->target != dispPtr->windowAtom)) {
+               atomString = Tk_GetAtomName((Tk_Window) winPtr,
+                       selPtr->target);
+               atomLength = strlen(atomString) + 1;
+               if ((length + atomLength) >= maxBytes) {
+                   return -1;
+               }
+               sprintf(buffer+length, " %s", atomString);
+               length += atomLength;
+           }
+       }
+       *typePtr = XA_ATOM;
+       return length;
+    }
+
+    if (target == dispPtr->applicationAtom) {
+       int length;
+       Tk_Uid name = winPtr->mainPtr->winPtr->nameUid;
+
+       length = strlen(name);
+       if (maxBytes <= length) {
+           return -1;
+       }
+       strcpy(buffer, name);
+       *typePtr = XA_STRING;
+       return length;
+    }
+
+    if (target == dispPtr->windowAtom) {
+       int length;
+       char *name = winPtr->pathName;
+
+       length = strlen(name);
+       if (maxBytes <= length) {
+           return -1;
+       }
+       strcpy(buffer, name);
+       *typePtr = XA_STRING;
+       return length;
+    }
+
+    return -1;
+}
+\f
+/*
+ *----------------------------------------------------------------------
+ *
+ * LostSelection --
+ *
+ *     This procedure is invoked when a window has lost ownership of
+ *     the selection and the ownership was claimed with the command
+ *     "selection own".
+ *
+ * Results:
+ *     None.
+ *
+ * Side effects:
+ *     A Tcl script is executed;  it can do almost anything.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static void
+LostSelection(clientData)
+    ClientData clientData;             /* Pointer to LostCommand structure. */
+{
+    LostCommand *lostPtr = (LostCommand *) clientData;
+    Tcl_Obj *objPtr;
+    Tcl_Interp *interp;
+
+    interp = lostPtr->interp;
+    Tcl_Preserve((ClientData) interp);
+    
+    /*
+     * Execute the command.  Save the interpreter's result, if any, and
+     * restore it after executing the command.
+     */
+
+    objPtr = Tcl_GetObjResult(interp);
+    Tcl_IncrRefCount(objPtr);
+    Tcl_ResetResult(interp);
+
+    if (TkCopyAndGlobalEval(interp, lostPtr->command) != TCL_OK) {
+       Tcl_BackgroundError(interp);
+    }
+
+    Tcl_SetObjResult(interp, objPtr);
+    Tcl_DecrRefCount(objPtr);
+
+    Tcl_Release((ClientData) interp);
+    
+    /*
+     * Free the storage for the command, since we're done with it now.
+     */
+
+    ckfree((char *) lostPtr);
+}