With our current Windows client, it's no longer possible to send PrintScreen. It was possible with 1.3.2, but this functionality was never ported to the VNC4. See bug 84 and 799. Wallace Valentim <wvalentim@thinlinc.com.br> has asked about this.
When implementing this, first check if this functionality is available in any RealVNC version.
Should be fixed. Verify.
Tested using Win7 and xev in session, printscreen key does not go thru the session until the options dialog is opend and ok is pressed, after that the printscreen key is handled in the session.
When running remote session initially in fullscreen the printscreen is not working and if i press alt-tab i switch among window applications, when going back to the remote session alt-tab is pass thru to the session and printscreen is working as expected. Clicking in view window does not solve focus issue. When running in windowed mode i was not able to get the printscreen key work at all.
Should be fixed. Retest.
Tested using client build 3913 on Win7 machine. Works as expected.