[Gtk2hs-commit] (main branch): Add mainDoEvent.

[Andy S. <And...@co...>]

diffing dir...
Wed Jun 30 23:08:36 EDT 2010  Andy Stewart <laz...@gm...>
  * Add mainDoEvent.
  Ignore-this: 37cd08eb71f1eb3e77f09f04a02c5e3
    {
    hunk ./gtk/Graphics/UI/Gtk/General/General.chs 52
    +  mainDoEvent,
    hunk ./gtk/Graphics/UI/Gtk/General/General.chs 91
    +import Graphics.UI.Gtk.Gdk.EventM (EventM)
    +import Control.Monad.Reader (ask)
    +import Control.Monad.Trans (liftIO)
    hunk ./gtk/Graphics/UI/Gtk/General/General.chs 254
    +-- | Processes a single GDK event. This is public only to allow filtering of events between GDK and
    +-- GTK+. You will not usually need to call this function directly.
    +-- [_$_]
    +-- While you should not call this function directly, you might want to know how exactly events are
    +-- handled. So here is what this function does with the event:
    +-- [_$_]
    +--  1. Compress enter/leave notify events. If the event passed build an enter/leave pair together with
    +--     the next event (peeked from GDK) both events are thrown away. This is to avoid a backlog of
    +--     (de-)highlighting widgets crossed by the pointer.
    +--    [_$_]
    +--  2. Find the widget which got the event. If the widget can't be determined the event is thrown away
    +--     unless it belongs to a INCR transaction. In that case it is passed to
    +--     'selectionIncrEvent'.
    +--    [_$_]
    +--  3. Then the event is passed on a stack so you can query the currently handled event with
    +--  'getCurrentEvent'.
    +--    [_$_]
    +--  4. The event is sent to a widget. If a grab is active all events for widgets that are not in the
    +--     contained in the grab widget are sent to the latter with a few exceptions:
    +--    [_$_]
    +--       * Deletion and destruction events are still sent to the event widget for obvious reasons.
    +--        [_$_]
    +--       * Events which directly relate to the visual representation of the event widget.
    +--        [_$_]
    +--       * Leave events are delivered to the event widget if there was an enter event delivered to it
    +--         before without the paired leave event.
    +--        [_$_]
    +--       * Drag events are not redirected because it is unclear what the semantics of that would be.
    +--        [_$_]
    +--     Another point of interest might be that all key events are first passed through the key snooper
    +--     functions if there are any. Read the description of 'keySnooperInstall' if you need this
    +--     feature.
    +--    [_$_]
    +--  5. After finishing the delivery the event is popped from the event stack.
    +mainDoEvent :: EventM t ()
    +mainDoEvent = do
    +  ptr <- ask
    +  liftIO $ {#call main_do_event #} (castPtr ptr)
    +
    }