Created attachment 35838 [details] [review]
proposed patch

This patch tries to handle WM_DESTROYCLIPBOARD and append a corresponding
selection clear event for it. After removing the artificial GDK_SELECTION_EVENT
in  gdk_selection_send_notify_for_display(), I cannot reproduce the problem
described in the comment block of the function.

Patch looks reasonable. I don't like the name of the
_gdk_selection_filter_clear_event() function, though, that name sounds like the
fnction clears some event. Why not just make the filter_clear_event variable
global (and name it a bit better)? We use lots of other global variables in
gdk/win32.

Is there a slight race possibility, if some other process calls EmptyClipboard()
at the same time, and the WM_DESTROYCLIPBOARD caused by that then also ends up
getting ignored? But that's hardly anything worth losing sleep over?

> I don't like the name of the
> _gdk_selection_filter_clear_event() function
The name was first stolen from gdkslection-x11.c, but eventually it does 
nothing more than return a variable. I agree that using global variable is 
better.

> Is there a slight race possibility, if some other process
> calls EmptyClipboard() at the same time, and the
> WM_DESTROYCLIPBOARD caused by that then also ends up getting ignored?
Probably no. From MSDN, OpenClipboard() "prevents other applications from 
modifying the clipboard content". "Modifying" should includes clipboard 
emptying.

Patch applied to HEAD and gtk-2-6, thanks!

	Fix for #163702, from Ivan Wong: 
	
	* gdk/win32/gdkprivate-win32.h 
	* gdk/win32/gdkglobals-win32.c: New flag _ignore_destroy_clipboard.
	
	* gdk/win32/gdkevents-win32.c (gdk_event_translate): Handle
	WM_DESTROYCLIPBOARD. Unless _ignore_destroy_clipboard, generate a
	GDK_SELECTION_CLEAR event.

	* gdk/win32/gdkselection-win32.c
	(gdk_selection_owner_set_for_display): Set _ignore_destroy_clipboard
	when emptying the clipboard ourselves.

	(gdk_selection_send_notify_for_display): Remove the artifical
	GDK_SELECTION_CLEAR event generation.