- * Transparency effect. We really want to check
- * current_graphics_mode->alphablend, but as of this writing
- * that's never set, so we do something lame.
+ * As of this writing, a value of zero for
+ * current_graphics_mode->alphablend can mean either that the tile set
+ * doesn't have an alpha channel or it does but it only takes on values
+ * of 0 or 255. For main-cocoa.m's purposes, the latter is rendered
+ * using the same procedure as if alphablend was nonzero. The former
+ * is handled differently, but alphablend doesn't distinguish it from
+ * the latter. So ignore alphablend and directly test whether an
+ * alpha channel is present.