To fix this issue on Ubuntu, edit these two files:
- Replace 'KeyboardLayout = (User Profile)' with 'KeyboardLayout = US-International' (or your preferred keyboard layout)
- Replace 'UseLocalIM=True' with 'UseLocalIM=False'.
If the sticky Ctrl key issue is still not fixed, update Ubuntu system settings to not show the mouse location when Ctrl key is clicked. Instructions can be found here.
If the issue still persists, try these links:
- Citrix forums: CTRL key sticking
- Citrix forums: CTRL Key Stuck
- ServerFault: Why is my Linux ICA client unable to use the “CTRL” key?
- CitrixICAClientHowTo (contains installation instructions for Ubuntu)