For work, I run Windows applications in my Mac frequently using Citrix. I have GNU Emacs for Windows installed on the Citrix machine so dealing with text editing is easier. Meta key mapping was screwed up by default. No matter what kind of lisp code I used or settings I changed I couldn’t get my Alt/Option or Command key to act as Meta (say for M-x). I either had to do Esc-x or Option-Command-x which are both equally horrendous.

After a while I found out this keyboard mapping setting tucked away in Citrix client. When you have any Citrix apps open, if you click Citrix Viewer->Preferences->Keyboard you’ll see Send Alt character using setting and then a dropdown option containing two choices. The default being Option-Command. I switched it to use Command. I would’ve preferred if there was just an Option remap to Alt but sadly there wasn’t. So it appears Citrix modifies the keys sent from my Mac keyboard to windows apps and remapping this key made emacs more usable.

Now I can do Command-x for M-x

Citrix Viewer Preferences for Keyboard

Send Alt Characters Using Setting