widget-checkbox-action should clear undo

[martin rudalics]

With Emacs -Q do M-x customize-face RET lazy-highlight RET

             [ ] Foreground: *
             [X] Background: paleturquoise (sample)
             [ ] Stipple: *
             [ ] Inherit: *

uncheck the box preceding "Background"

             [ ] Foreground: *
             [ ] Background: *
             [ ] Stipple: *
             [ ] Inherit: *

and undo, gets me:

             [ ] Foreground: *
             [ ]              [ ] Stipple: *
             [ ] Inherit: *

`undo' should be cleared here.  The patch below does this.


*** wid-edit.el Thu Dec 15 11:32:48 2005
--- wid-edit.el Fri Dec 16 10:42:40 2005
***************
*** 2161,2167 ****
      (when sibling
        (if (widget-value widget)
          (widget-apply sibling :activate)
!       (widget-apply sibling :deactivate)))))

  ;;; The `checklist' Widget.

--- 2161,2168 ----
      (when sibling
        (if (widget-value widget)
            (widget-apply sibling :activate)
!         (widget-apply sibling :deactivate))
!       (widget-clear-undo))))

  ;;; The `checklist' Widget.