Re: Have there been recent changes in DnD?

[Fred Kiefer]

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.

Not using GNUmail myself, this is as much as I can advice you on the
problem.