[maemo-developers] Treeview drag and drop

[From: Jeffrey Barish]

Owen Williams wrote:

> I find I have to tape and select the item, then tap and hold to get it
> to drag and drop.  If I tap to select and immediately start dragging, I
> get the multi-select thing.

No, actually for me it works fine to drag at the same time that I select,
but the drag still doesn't register until I leave the widget where the drag
started.  The behavior is the same whether or not the item (a row in a
treeview) was selected first.

> If your treeview does not have multiselect, that sounds like a gtk bug.

My treeview does not have multiselect.  The mode of the treeview is the
default SELECTION_SINGLE.

I tried activating the drag explicitly using drag_begin in a motion_notify
handler and also implicitly without such a handler.  I presume that the
implicit method uses the same drag_check_threshold, so it isn't surprising
that I observe the same behavior in both cases.  I think that there is
something wrong with the way drag_check_threshold works on maemo.

I had the idea that I should write my own drag_check_threshold.  I learned
that I get one event when I first tap.  When I then drag the stylus, I get
no more events until I leave the treeview.  I have GDK_BUTTON_MOTION_MASK
set (in Glade), so I expect to receive a barrage of events when I move the
stylus.  I also expect that the distance of the first tap will always be 0,
but it is not.  Often it is 0, sometimes it is a small number (e.g., 1-3),
and rarely it is a large number (e.g., 14.0, 39.1).  If I set my threshold
to > 0.0, then I am sometimes able to initiate a drag without tracing to a
point outside the treeview.
-- 
Jeffrey Barish