Please describe the problem:
Nautilus grab the mouse when rising a modal dialog as popup when something wrong
append (like trying to delete a file, if you're not allowed). Durring a drap&drop, 
you will not be able to release the "drag&drop" (because of the modal dialog),
and you cannot click on cancel or ignore, because of drop cursor. Then, "desktop
mouse locked" 

Steps to reproduce:
1. Start delete files with nautilus, knowing that you havent the right (unix
right) to do for some. 
2. Start an "Drag and Drop" of an (other) file, on the desktop
3. Don't release the button (don't drop) until nautilus show a popup modal
dialog that tel that you cannot delete a file.
4. Nautilus show his popup (modal dialog to tell you that you cannot remove some
file), and you cannot click on Cancel or Ignore, and you cannot drop file file.
5. That's all, the mouse is grabed




Actual results:
Mouse definitively grabed, no click possible on the desktop

Expected results:
Nautilus should show a dialog always over the others, but no grab the mouse

Does this happen every time?
yes

Other information: