As a matter of fact, since you started this thread, I've updated the client with a new way to process clicks. This happened at the time of the latest patch. So just to be sure: Have you tried again since then?
If you have, please try two other things:
1) Please try the old client and check whether it works there.
2) Run the console command :clickdb on in the client to enable click-output debugging. Once you do that, try to click somewhere, and the client should dump three files, click1.png through click3.png, in your home directory. Please post those files.