Backport: Ensure focus for a newly opened dialog
Ensure that the child widgets of a freshly opened dialog can be immediately traversed with the Tab key. Currently, the contents of each dialog are repackaged into a Gtk::ScrolledWindow for the purpose of better controlling the scrolling behaviour. This ScrolledWindow must not steal the focus from the widgets that the user cares about.
Fixes #3482 (closed)
Backport of !4379 (merged)