Focusing of a window only occurs if you click on the title bar (sometimes) but in most cases the window will only focus when you are moving the application (gnome and non-gnome) instead of any area inside of window which is the correct behaviour.

Mouse interaction works if there are drop-downs and input boxes, meaning you can select and change items with the mouse, but the window still has no focus. If the window has an input box for keyboard interaction, typing in the window after clicking the input box, redirects keyboard input to the last application that has focus, or if no other application is open, no keyboard input is shown.

Steps to reproduce
- Install Ubuntu Gnome
- Set Window Action Key to Disabled in Gnome Tweak Tool
- Ensure Focus Mode is set to Click (default)
- Open two applications
- Try typing in one window and then the other

Additionally, doing the following does not work as well:
- Creating a new user account and setting the Window Action Key = disabled and Focus Mode = Click . Tested only Ubuntu Gnome 14.10 + Main + Staging PPA.
- Setting Window Action Key = disabled and Focus Mode = Click and logging out or rebooting and logging in again. Tested only Ubuntu Gnome 14.10 + Main + Staging PPA.

This was originally filed here: https://bugs.launchpad.net/ubuntu-gnome/+bug/1407085 and also has a video available to demonstrate the problem.