===================================================================
RCS file: /cvs/ace/ace/lib/xwin.c,v
retrieving revision 1.9
retrieving revision 1.10
diff -p -u -r1.9 -r1.10
--- ace/lib/xwin.c	2012/03/24 18:02:04	1.9
+++ /cvs/ace/ace/lib/xwin.c	2015/05/31 13:03:36	1.10
@@ -441,6 +441,8 @@ xwin_nextevent (XWin_Event *ev)
 
       case MotionNotify:
 
+	if (!(event.xmotion.state & ButtonMask))
+	  break;
 	while (XCheckMaskEvent(display, ButtonMotionMask, &event));
 	if (!XQueryPointer(display, event.xmotion.window,
 			   &root, &child, &root_x, &root_y,