Window headerbar is hidden at all times. We do not want to execute the logic that comes with GtkHeaderBar, so we simplify it by using GtkBox as a dummy widget.
This avoids D&D controllers clash and allows to freely customize how maximize, minimize and close buttons work (differently for e.g. web application) and where are they placed
The "clapper_src" directory name was unusual. This was done to make it work as a widget for other apps. Now that this functionality got removed it can be named simply "src" as recommended by guidelines.
