I use VirtualBox to host a Windows 7 virtual machine on my Kubuntu system. This is mainly for running Photoshop Elements.

A common requirement in Elements is to pass alt-click through, for example when chosing a source area when doing a clone stamp. By default, this doesn't work for me because the host operating system is picking up the alt click and un-maximising the window.

To change this, you need to alter KDE settings. Open System Settings on the computer tab of the K menu. Open the Window Behaviour option. Choose Window Behaviour from the left hand menu and the Window Actions tab. Change the modifier key from Alt to Meta.

It will now work as expected. This example was done on KDE 4.6.5.