New fancy experiment to make labels both selectable _and_ focusable, so
* src/aboutdialog.cc (SelectableLabel): New fancy experiment to make labels both selectable _and_ focusable, so that they end up in the Tab chain. * src/aboutdialog.cc src/imagebutton.cc src/prefdialog.cc: Don't show all children of custom "composite" widgets in the constructor. It doesn't make much sense since we call show_all() later on anyway. And making these "composite" widgets really independent components would require overriding both show_all_vfunc() and hide_all_vfunc(), which is currently not worth the effort.