Offset context menu in Manager to avoid accidental clicks

Small fix to Qubes Manager to open the context menu slightly to the
right of the mouse to avoid accidental clicks. Originally created by
@unman , ported to 3.2 branch.

references QubesOS/qubes-issues#1831

qubesmanager/main.py

@@ -1701,7 +1701,7 @@ def createPopupMenu(self):
         return menu
 
     def open_tools_context_menu(self, widget, point):
-        self.tools_context_menu.exec_(widget.mapToGlobal(point))
+        self.tools_context_menu.exec_(widget.mapToGlobal(point + QPoint(10,0)))
 
     @pyqtSlot('const QPoint&')
     def open_context_menu(self, point):