Win: Subclass richtext controls and port the OS/2 MLE context menu code to it. OS/2: Add missing Delete menu item from the MLE context menu. Reorder the menu and disable menu items instead of removing them from the menu completely. This is consistent with how these menus behave on Windows, and has the benefit of the menu items always being in the same place. ENTRY_DELETE handlers may need to be added to the special Unicode edit handler functions. The OS/2 code has not been tested yet, follow up commits may be needed. Menu identifiers 60001 to 60999 are now reserved for internal DW use.