The normal mode of Dittoing someone else's Photon session (specifying -n) is to have a single cursor that can be controlled by either the local or
            remote user. Similarly, keystrokes from either keyboard can be entered into the application
            with keyboard focus, which is normally what you want for a remote training or debugging
            session.
         
         
         
         Offscreen context
            support is enabled by default, though you can turn it off with the -OO
            option. 
         
         
         
         Offscreen context support has some limitations:
               - The support of the offscreen
                  contexts via phrelay is limited to uncomplicated cases where applications do
                  regular draws followed by periodic blits from offscreen to the main display. This
                  means: 
 
                     - The PdGetOffscreenContextPtr() function isn't supported.
                        
                     
- The creation of offscreen locks isn't implemented. 
 
- These functions aren't supported by Phindows: 
 
                     - PdGetOffscreenSurface()
                        
                     
- PdDupOffscreenContext()
                        
                     
- PdCreateDirectContext()
                        
                     
 
- Using Phindows to connect to a Photon session where offscreen
                  contexts currently exist or were previously orphaned will cause the software to
                  attempt to re-create and re-draw those contexts. The accuracy that results depends on
                  how well the applications currently running handle invalidation of their offscreen
                  contexts. 
               
- Offscreen context support is disabled when you connect to remote
                  hosts running older versions of phrelay.