winex11.drv: Empty clipboard cache on process unload to avoid false positives…

dlls/winex11.drv/clipboard.c

@@ -3282,3 +3282,13 @@ void X11DRV_SelectionClear( HWND hWnd, XEvent *xev )
         X11DRV_CLIPBOARD_ReleaseSelection( event->display, event->selection,
                                            event->window, hWnd, event->time );
 }
+
+/***********************************************************************
+ *           X11DRV_Clipboard_Cleanup
+ */
+void X11DRV_Clipboard_Cleanup(void)
+{
+    selectionAcquired = S_NOSELECTION;
+
+    X11DRV_EmptyClipboard(FALSE);
+}

dlls/winex11.drv/x11drv.h

@@ -765,6 +765,7 @@ extern XContext winContext;
 
 extern void X11DRV_InitClipboard(void);
 extern int CDECL X11DRV_AcquireClipboard(HWND hWndClipWindow);
+extern void X11DRV_Clipboard_Cleanup(void);
 extern void X11DRV_ResetSelectionOwner(void);
 extern void CDECL X11DRV_SetFocus( HWND hwnd );
 extern Cursor X11DRV_GetCursor( Display *display, struct tagCURSORICONINFO *ptr );

dlls/winex11.drv/x11drv_main.c

@@ -583,6 +583,7 @@ static void thread_detach(void)
  */
 static void process_detach(void)
 {
+    X11DRV_Clipboard_Cleanup();
 #ifdef SONAME_LIBXXF86VM
     /* cleanup XVidMode */
     X11DRV_XF86VM_Cleanup();