... in the overflow toolbar. Using ToolBoxMenuType::NONE
is wrong as it might affect the layout. Can be easily triggered
here by adding FloatWinPopupFlags::GrabFocus to StartPopupMode
(which likely will be needed to fully solve tdf#79657).

Another case was fixed in 91053763
("Fix sub-toolbar tearoff for .uno:ChooseControls"), but without
providing a solution for the context menu.

Change-Id: I4a0b4560fe49106613fa2337b5dd83eb7fa29f47
Reviewed-on: https://gerrit.libreoffice.org/46837Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Maxim Monastirsky <momonasmon@gmail.com>