Merge branch '3571_high_level_mouse_api'

Merge branch '3571_high_level_mouse_api'

* 3571_high_level_mouse_api: (28 commits)
  Rename mouse.was_drag to mouse.last_msg.
  Drop old mouse API and use the new one.
  Fix menu handling.
  Optimize menu activation.
  mcedit: rename MCEDIT_DRAG_NORMAL to MCEDIT_DRAG_NONE.
  mcedit: use the new mouse API.
  WEdit: get rid of mouse event pump.
  WEdit: use the new mouse API.
  Help: use the new mouse API.
  Viewer: use the new mouse API.
  Diff viewer: usethe new mouse API.
  WTree: use the new mouse API.
  (panel_mouse_callback): minor optimization.
  WPanel: use the new mouse API.
  WMenuBar: execute menu item after drag action.
  WMenuBar: a few mouse handling fixes.
  WMenuBar: use the new mouse API.
  WRadio: use the new mouse API.
  WInput: use the new mouse API.
  WCheck: use the new mouse API.
  ...