Description of problem: While using the Gnome OSK, you will notice the special characters will not react to button presses of the OSK.

Steps to Reproduce:
1. Open Gedit
2. Using the OSK, press and hold a, e, i or o and release.
3. Click any of the Umlaut characters in the pop up.

Actual results: Nothing happens, special character is not inputted.

Expected results: All special characters work using the OSK.

Additional info: This bug ONLY applies to X11 sessions, Wayland works completely as expected. Setting component to Mutter as this was the problem last time this bug popped up.