It looks like the RDP support some windows key shortcuts for some specific actions, looks at this post for more information:
Additional, you can configure some actions in the RDP to optimize the user experience:
"Configuring a resource for RDP remote desktop web access"
Hope it´s help.
We use 'Server Type' = 'Remote Desktop Web Access'.
So there is an HTTPS connection to the RDP server and this opens a new RDP connection to the end server as the user is prompted to enter the hostname.
In the 'Custom Parameters', it is included 'keyboardhook:i:2' whis is echoed back to the .rdp file - that's Ok. However, the Windows Key combinations that usually works in our computers, don't work there.
In this document says that the 'Windows key combinations' work for 'Remote Desktop Web Access' (Server Type):
I will check this out.