gnome-shell: activate entry on focus

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
gnome-shell: split function

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
gnome-shell: handle escape

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>
gnome-shell: use clutter constants

Signed-off-by: Marc-Antoine Perennou <Marc-Antoine@Perennou.com>