Citrix

https://support.citrix.com/article/CTX140219

The following hotkey combinations were introduced in version 10.100 of the Presentation Server for Windows Client:

• SHIFT + F2 - Full-Screen to Windowed
  The SHIFT + F2 hotkey command allows switching an ICA session window from a Full Screen to a Windowed mode and the reverse is also true.
  Usage: Inside the ICA session window, press SHIFT + F2 on the keyboard and the ICA session switches to Windowed mode. Reverse is also true.
  
• SHIFT + F11 – Minimize Full Screen ICA session window
  The SHIFT + F11 hotkey command allows minimizing full screen ICA session window.
  Note: This behavior has been reverted in versions 10.214, 10.223, 10.225, 10.230, 11.00 and later so that the default behavior no longer minimizes the session; instead, the key sequence is passed to the session (for more information, see CTX115230 - Understanding Shift+F11 Key Combination Behavior.
  
• SHIFT + F12 – Restore Full Screen ICA session
  The SHIFT + F12 hotkey command restores the minimized or resized ICA session window to the original size.