They are not updated after switching tabs. Thus they can be enabled even
when no entry is selected: select an entry on the current tab and then
switch to an empty tab.
Emit AddressWidget::selectionChanged() signal after changing the current tab
to update these actions.
Change-Id: I00da15ed6c3d3839210ae3ffbe1436e234695522
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>