Re: [gtkmm] canvas event hierarchy

[Paul Davis <paul linuxaudiosystems com>]

>Am Mon, 2003-04-07 um 13.27 schrieb ERDI Gergo:
>> On 7 Apr 2003, Nabil Sayegh wrote:
>> 
>> > I reparent() the clicked column to the canvas and drag it over the other
>> > table. I expected the other columns in the target table to also receive
>> > the GDK_MOTION_NOTIFY but they dont. (I return false in the
>> > on_item_event).
>> 
>> Some canvas items only recieve events if/where they are filled.
>
>Thanks for your answer.
>The items are filled. Actually the column which i drag has the same
>content as all the other columns.
>But I need to send MOTION_NOTIFYs while dragging to the other items.

X (and GDK and GTK and the canvas) don't work this way.

there is an implicit grab of the pointer when the button press
occurs. this exists at two levels: GDK will ensure there is a
server-level grab because the underlying widget has asked for press
and release events. but there is also a canvas-level grab that ensures
that the item which is handling the button press gets all events
(well, actually, those that are asked for) until the button-release
occurs. the canvas part of that is from memory, so don't trust me on
this. 

i have written a lot of canvas code, and i have not needed the
functionality you describe. perhaps you need to explain why you think
you need it. i just keep track of the various item's locations (or ask
them for it), and then figure out where the drag ends using that.

--p