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.
I can confirm this issue. Started kmail; can move mails to different folders; start blender; cannot drag anymore, in running kmail instance. Note: logout and login (via KDM) "fixes" the problem - until blender is started again...
That started only 2 months ago or so (running now debian on amd64, kmail 1.13.7, kde 4.8.4); are there any more details I can offer to hunt that down?
I am pretty sure it is a Blender bug, because it is not only KMail that is affected, see bug 308491.
But if kmail lets itself disturb by other programs in this way, I'd see it as a bug in kmail, too. Well, how can I see what the cause for the problem is? Trace dbus?
I think that since kmail and blender are executed by the same user, with the same privileges, and depending on what the exact problem is, it may not be easy preventing blender from disturbing kmail. When I reported the bug, I was aware that it could be a blender bug, or even a dbus bug, but, as I see it, it's kmail that is being affected, and the only practical way to find out what is happening, I think, is tracing back the problem from kmail misbehaviour (or from bug 308491, which seems to be almost the same problem) to its source and, should be discovered that blender overwrites some file, or some variable, or whatever when it shouldn't (or maybe dbus doesn't protect some data when it should, or some other non KDE related problem), then that can be reported as a bug to the program developers. But if I report the bug to blender (or dbus) developers, with just the little information I have now, I doubt they will be able to find what's wrong, since probably they would need first to get familiar with KDE code, and so, I suspect kmail will continue to have this problem for a long time. On the other hand, if I can tell blender (or dbus) developers that the problem is, say, that some variable that should have been left alone is overwritten when blender starts, then it is much more likely that the bug will be fixed quickly. My point is that, even if the bug is not necessarily kmail's fault (and remember that the bug could be too in some KDE library, for all we know), the only practical way I can see to debug it is by finding how this misbehaviour is triggered in kmail, and reporting those finds to the developers of the guilty program, if it's not kmail.
If it's not just kmail which is affected I report it to kdelibs
As found out in bug 308068, this a Blender bug.
Of course I meant bug 308491 :)
Blender 2.65 came out so I updated my binaries. I can confirm that after opening Blender, drag and drop support no longer breaks on my KDE desktop, so the problem is solved.
I can confirm too that with blender 2.65 the issue disappeared in kmail. Thanks to everyone involved!