Version: (using KDE 3.5.9) Installed from: Compiled From Sources Compiler: GCC 4.2.4 OS: Linux This is ocurring in the current KDE-3.5 SVN BRANCH. When I have two X sessions running and switch from A to B and then from B back to A, it causes spurious input in session A. Test case. Using the first X session (console 7) and with another X session running (console 8) Make sure that there is something in Klipper. Open a document in KWrite. Switch to session :1 and back using <Ctrl><Alt>Fn. Many times, something gets pasted into the document. If I am using Konqueror/KFM when I make the switch, it will often display an error dialog or switch from KFM to displaying a file.
sounds familiar. i'm relatively sure this a known x server bug. please search the xorg bugzilla.
Having consulted the Xorg Bugs and mailing list. I find that the problem is that switching from a Virtual Terminal to a KDE X session can result in spurious mouse event input and specifically a spurious paste. I didn't find a current bug for Xorg on the Free Desktop bugzilla. I did find an email on the list: http://lists.freedesktop.org/archives/xorg/2007-October/029658.html
Pavel Troller advised me that this is an Xorg bug and has been fixed in their GIT repository.