bug#31968: 26.1.50; Allow to hide title bar on maximize (gtk/gnome/csd)

[martin rudalics]

> That would be a somewhat bigger patch. Iʼm assuming weʼd need to
> adjust nsgui and w32gui frame parameter definitions as well.

For non-GTK builds we'd have to proceed as follows:

(1) When we do the maximization ourselves, remove the decorations
    first and then maximize.

(2) When we get a maximize event, remove the decorations.

(3) For any event or action that removes the maximized state, re-add
    the decorations provided the frame should not stay undecorated via
    a frame parameter.

So this would require some quite substantial coding effort and should
definitely wait until someone confirms that your GTK patch works.

martin