[news.eclipse.tools.gef] Object creation with DnD from the palette preve

[Pascal Gelinas <pascal.gelinas@xxxxxxxxxx>]

Hi all,

I have a simple graphical editor to help the creation and edition of a 
xml file of our specific format. It uses pretty much everything in gef, 
creation of object, connection, anchor points, etc.

Today, I wanted to add the ability for the user to create a new object 
using the DnD facility of the palette. Previously, a user had to click 
on the palette then click in the editor, which then launched the command 
to create the object in the model. It also launched the direct edit of 
the newly created object to cut down operations done by the user (so the 
user doesn't have to select then click the object to activate direct 
edit). Everything worked fine.

Now, when the user creates the same object using the DnD facility, the 
user cannot directly start typing the new value because of an 
inconsistent state of the keyboard focus. The TextCellEditor doesn't 
have the keyboard focus, so user input is not directed to it. Also, this 
leaves the CellEditor open when it should be closed because it doesn't 
have the focus.

I've tried pinning down the problem and I think I might have found it. 
When using point-and-click to create the object, it is the CreationTool 
class that handles the mouse down event. When mouse down happens, it 
calls the performCreation() method which execute the creation command 
(in my case it's a compound command which creates the model object then 
start direct edit) then select the new object by calling 
selectAddedObject(EditPartViewer).
When using DnD to create the object, it is the 
TemplateTransferDropTargetListener class that handles the drop event. 
When the drop happens, the method handleDrop() is called by the super 
class, AbstractTransferDropTargetListener, which is overridden to select 
the created object. The base handleDrop execute the creation command as 
the CreationTool does. The extended method select the new object by 
calling selectAddedObject() which is a copy of the previous method. If 
you look closely at the two methods, there is a difference: the second 
one calls
viewer.getControl().forceFocus();
and the first one doesn't. I think this call is the problem.

As a test, I copied the TemplateTransferDropTargetListener and removed 
that call. Everything seems to work fine now when using the DnD. So, I'm 
wondering if this is valid enough to open a bug to change this behavior 
or is there a reason behind that call that I'm unaware of?

I'm using Gef 3.5.
--
Pascal Gélinas | Software Developer
*Nu Echo Inc.*
http://www.nuecho.com/ | http://blog.nuecho.com/

*Because performance matters.*