display-page: Make use of 'linked' style
display-page: Make use of 'linked' style

Instead of using '0' spacing between fullscreen/restore & properties
buttons, put them in a box and set 'linked' style on the box.

This fixes the issue of fullscreen/restore button being chopped on the
left side.

https://bugzilla.gnome.org/show_bug.cgi?id=707293

vbenes/gnome-boxes,vbenes/gnome-boxes