* basep-widget.[ch] : Rename "focus_panel" signal to "move_focus_out"
as same action (Ctrl+Tab) on DrawerWidget moves focus from
DrawerWidget to Drawer. Add code to basep_widget_move_focus_out()
to implement moving focus from DrawerWidget to Drawer.

(basep_widget_construct) Sink BasePPos to avoid warning on panel
deletion.

* drawer-widget.c (drawer_widget_new): Do not allow panel in
DrawerWidget to receive focus.

* drawer.h (Drawer): Add two new fields moving_focus and jyst_focused.
The field moving_focus is used to prevent drawer being closed
when keyboard focus moves from Drawer to DrawerWidget and being
opened whem keyboard focus moves from DrawerWidget to Drawer
The field just_focused is used to prevent the drawer being closed
when a Drawer, which does not have focus, is clicked.

* drawer.c: Add signal handlers for focus_in_event, focus_out_event
and key_press_event on Drawer.
focus_in_drawer ensures that drawer is opened when focused
focus_out_drawer ensures that drawer is closed when unfocused
key_press_drawer implements arrow keys to move focus from Drawer to
DrawerWidget and focus the first or last object on the panel and Escape
to close the drawer.

* foobar-widget.[ch] : Rename "focus_panel" signal to "move_focus_out"

* panel-widget.c (panel_widget_focus): Do not focus panel for
DrawerWidget

* panel.c (panel_menu_get): Sink menu object to avoid warning on
panel deletion