Comment 12 for bug 153518

I don't think this is a gnome-applets bug. At least it occurs regardless of whether there is an accessibility applet present or not. If anything I would say it belongs against at-spi. But I believe there are several interacting accessibility-related packages, and it is hard to work out which of them is at fault.

A variant of this is reproducible in Intrepid.

Instructions:

Choose Preferences|Assistive technologies
"Enable assistive technologies" is checked (default)
Choose "Keyboard Accessibility"
Check "Simulate simultaneous keypresses", and "Disable sticky keys ..." is unchecked (default)
Click in the test box, press Shift A B and observe "Ab" as expected
Press Shift+A B and observe "Ab" and also that sticky keys has now been turned off

In other words "disable if two keys are pressed together" is always active even if it's not selected.