I did quite a bit of searching. I was just thinking there were more. I have a new work computer so my bookmarked websites did not get updated correctly do to slight corruption issue.
Anyway, I thought I had seen a KEY_GUI. I know there is a left and right version so I guess I just started doubting my memory.
I did too, when I first read your post. Just exactly where is the Arduino showing a Graphical User Interface? How else would keys relative to a GUI make any sense?
I am not using the typical Arduino board. I am using a special board that simulates keyboards and mice. I use it as an Administrator tool (wink wink wink). In my environment I have to setup users with special Remote Desktop Sessions as well as special desktop shortcuts. The great thing about this board is that you program it using the Arduino IDE.
So I write all of the commands out thru this device and it sets up the user very quickly.
Unfortunately, scripts are frowned upon by our IT group so I found this device and it saves me a ton of time.
The trick is getting the EXACT key combinations inorder to start the right service.