I run a number of VMWare virtual machine instances on my Linux host and in one of them I do a lot of Photoshop work. This involves a lot of holding down the Shift key, which with the default installation of Kubuntu 8.04 enables the sticky keys and slow keys accessibility options.
To turn this off, go to System Settings/Accessibility and click on the "Activation Gestures" tab. Then uncheck the "Use gestures for activating sticky keys and slow keys".
Click the Apply button and how you can hold down the Shift key as long as you’d like.