Host: Windows XP Pro
Guest: Slackware 12.2 updated to -current
VirtualBox: 2.2.0
Install Slackware 12.2 from the dvd and do all the upgrades to current which will have you running KDE 4.2.2 with qt-copy r948357 (KDE's version of QT with changes not yet made upstream). It has also been tried with various versions of the vanilla qt version.
The issue is whenever mouse integration is enabled, you are unable to sort by columns. When you click on it it highlights the entire area. This seems to happen in every qt4 based program. Click on Machine -> Disable Mouse Integration and you can then click on the columns and sort by whichever column you choose. Re-enable mouse integration and you are unable to sort anymore.