* keyboard.c (Qscrollbar_movement, Qvertical_scrollbar,
Qabove_handle, Qhandle, Qbelow_handle): New symbols.
(make_lispy_event): New code to build scrollbar clicks.
(make_lispy_movement): New code to handle scrollbar movement.
(head_table): Include Qscrollbar_movement in the event heads.
(syms_of_keyboard): Init and staticpro Qvertical_scrollbar,
Qabove_handle, Qhandle, and Qbelow_handle.
* keyboard.h (Qscrollbar_movement): Declare this along with the
other event types.
* lisp.h (Qvertical_scrollbar): Declare this.
* window.c (window_from_scrollbar): New function.
* window.c (Fset_window_configuration): Don't restore the frame's
focus redirection if the target frame is now dead.