I can confirm what Paul Hirst said above, it seems to happen when tool tips or drop down menus. It happens with these types of windows: Menu, PopupMenu, DropdownMenu, Dialog, ModalDialog, Tooltip, Notification, Utility.
I can confirm what Paul Hirst said above, it seems to happen when tool tips or drop down menus. It happens with these types of windows: Menu, PopupMenu, DropdownMenu, Dialog, ModalDialog, Tooltip, Notification, Utility.