102/16

[Matthew Flatt <mflatt@cs.utah.edu>]

The exp-tagged source for MzScheme and MrEd in the CVS repository is
now version 102/16.

The main change is that text fields, by default, react to a
right-button release with a popup menu of edit commands (as a Windows
user would expect).

This feature turned out to be one of those seemingly simple tasks that
exposes a chain of little gaps in the GUI toolbox. Hence the following
changes in 102/16:

 * Added `can-do-edit-operation?' method to editor<%> and snip%.

 * Changed `append-editor-operation-menu-items' to add menu items
   that are grayed out (on demand) when they do not apply to the
   target editor.

 * Added `popup-menu' method to editor-admin% and snip-admin%.

 * Added `get-popup-target' method to popup-menu%. It returns a
   canvas<%> or editor<%> object, depending on how the menu was popped
   up, or #f if it isn't currently popped up.

 * Added "leftbuttonseq", "middlebuttonseq", and "rightbuttonseq" to
   the set of virtual event names recognized by keymap%'s
   `map-function'. Whereas "leftbutton", etc. call the handler
   procedure only for button press events, "leftbuttonseq", etc. call
   the handler for the full sequence of button events from press to
   release.

 * Changed the default text keymap initializer to map right button
   releases to popup an edit menu.

Matthew