Re: Have there been recent changes in DnD?

[Andreas Schik]

On 2008-01-16 11:49:32 +0100 Andreas Schik <andreas.schik@web.de>
wrote:

> On 2008-01-14 13:10:17 +0100 Fred Kiefer <fredkiefer@gmx.de> wrote:
>
> > Andreas Schik wrote:
> > > On 2008-01-10 21:46:38 +0100 Fred Kiefer <fredkiefer@gmx.de> wrote:
> > >
> > > > Andreas Schik wrote:
> > > > > since I 'upgraded' to yesterdays SVN og GNUstep I do have problems
> > > > > with DnD in GNUMail. Have there been any changes in the underlying
> > > > > mechanisms making it necessary to change applications?
> > > > The basic mechanism hasn't changed since April last year. What has
> > > > changed a bit was the implementation for NSTableVie and 
> > > > NSTextView. Are
> > > > you using subclasses of these?
> > > It looks like GNUMail is using a subclass of NSTableView in the mail
> > > window. This table is the source of the operation. What I found out 
> > > so
> > > far is that the target of the operation (outline view) in the 
> > > method -
> > > outlineView:validateDrop:proposedItem:proposedChildIndex: receives
> > > NSDragOperationNone in the NSDraggingInfo object ([info
> > > draggingSourceOperationMask]), no matter which modifier I press 
> > > down.
> >
> > There has been one important change for dragging in NSTableView, 
> > which
> > may affect that code in some way. Now there are different drag mask
> > settings for local and non-local dragging. The later by default is 
> > set
> > to NSDragOperationNone. This behaviour matches, as far as I know, 
> > what
> > Apple is doing. But why would the drag view see this as a non-local 
> > drag
> > operation?
> >
> > What you should do is debug into GSDragView (and it's subclass XX) to
> > see, how the value for draggingSourceOperationMask is build up from
> > dragMask (coming from the drag source) and operationMask (coming from
> > the modifier keys). One of these two (most likely dragmask) must be 
> > wrong.
> Well, it is not a GNUMail problem, but a combination of GNUstep and
> Camaelon.
> Camaelon introduces a category for NSTableView that does not call the
> (assumedly new) selector -_initDefaults: Hence, the local dragging
> mask is 0. Fixing this remedies part of the problem. What remains is a
> quite strange behaviour:
> If I overlap the mailbox window and the mail window of GNUMail the
> operation works. As soon as there is a gap between the windows, i.e.
> the drag operation touches an external application, the operation
> again fails. It looks like GSDragView does not recognize that it must
> switch back from non-local to local operation. It did not debug this,
> though, and probabyl won't have time today to do so. But this might
> anyway help you to track it down.
This did let me sleep :-)
Find a patch attached to this mail that fixes GSDragView. It finally
came down to a missing ! operator.

Cheers,
Andreas

<GSDragView.patch>
--
Mail: andreas dot schik at web dot de
Home: http://www.andreasheppel.de

PGP Key is available from the MIT key server (pgp.mit.edu).

GSDragView.patch
Description: Text Data

pgp440esMwvOJ.pgp
Description: PGP signature