Fix for bug #1239832 where typing in overstrike mode was undone in two steps rather than one.
Fix for bug #1239832 where typing in overstrike mode was undone in two
steps rather than one.

windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,keperlia/foo-wsh-panel-mod.scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,keperlia/foo-wsh-panel-mod.scintilla,windoze/scintilla,windoze/scintilla,windoze/scintilla