I've found that if I ever start blender (the 3D drawing program) in a KDE session, drag and drop of messages to folders in kmail stops working. I can select and drag messages, but when the mouse pointer hovers over the folders, it doesn't change to the shape it usually does, and releasing the mouse button does nothing.

I've found this happening in Debian Lenny, Debian Squeeze, Kubuntu 10.04, Kubuntu 10.10, Kubuntu 11.04, kubuntu 11.10 and Kubuntu 12.04, both for 32 and 64 bits, using official kmail packages for each distribution always, and for blender versions at least from 2.6x, downloaded from the blender site (www.blender.org). In fact, it happens to me for all versions of blender and kmail I've tried (always in Linux, Debian or Kubuntu, 32 or 64 bits).

I use imap to connect to the mail server in all cases, but the problem appears both for local and remote imap folders. The configuration of the destination folder doesn't seem to matter either. I always list my messages by flat date, with classic view, so that might possibly be related to the problem

The problem appears from the moment I start blender, even is kmail is not on at the moment, and doesn't go away after switching off either blender of kmail. It does go away after I close the session and login again. I haven't detected this problem in any other KDE program, but kmail is the only program where I regularly use drag and drop, so the problem may not be restricted just to kmail, nor I've found any other problem but blender causing that effect.

It's not a very important issue, since I still can move messages around using the menus, but I find it a very surprising problem, since I can not fathom how could blender and kmail be interacting in such a way.

I've searched both internet and the KDE bug list for this bug, but I haven't found anything even remotely similar, so it may have something to do with my specific configuration. Yet, it happens to me in Debian Squeeze (that's kmail 1.13.5), where the configuration has been inherited and upgraded from the first KDE 3 versions), and in Kubuntu 1x.x, starting with a clean configuration from 10.04 (now at Kubuntu 12.04, and updated just two days ago).

I get this problem with 100% reproducibility. Every time I start blender, drag and drop stops working in kmail. If I don't start blender, drag and drop never stops working in kmail. While a session where I've started blender is running, drag and drop never works again for kmail in that session.

Reproducible: Always

Steps to Reproduce:
1. Install kmail in kubuntu 12.04 from packages
2. Download and install blender 2.64 from www.blender.org
3. Start blender
4. Try to drag messages from the message list in kmail to any folder
Actual Results:  
I can select folders and drag them, but I cannot drop them: releasing the mouse button seems to do nothing, yet no error message or warning appears. The background of the folder changes colour when the pointer hovers over it, but not the same colour I get when drop works.

Expected Results:  
The pointer should change shape when hovering over the destination folder, the background of the folder name should change colour, and when releasing the mouse button I should get a short menu asking if I want to copy or move the selected messages to the destination folder.

I have access to the Kubuntu computer only during weekends, so if you request additional tests with modern versions of kmail it may take a few days.