Right-Alt & Click on the display screen to open the external window doesn't work. All other ones work fine. Have reinstallt
more then 10 iimes, can't get it to work. My version is 1.100
Can some one give me a helping hand.

I can confirm that too, but it's not the CS717. I have now also noticed this problem with the FBW A320. Maybe you signed up as a beta tester for the SU15 update. I have changed some key assignments. For example, I can no longer use the arrow keys in the cockpit to move back and forth or left and right. It must be due to the update from Microsoft... Captain Sim is completely innocent...

Thanks Rudolf, no I'm not signed up as a beta tester for the SU15 update. I have not changed any key assignments. I can use the arrow keys in the cockpit to move back and forth or left and right. Looks like a update from Microsoft sim causing this problem.
Probably nobody has taken any notice jet.

I think I've found the problem, at least for me. The keyboard was set to short keyboard, I changed that to standard, now it works again

I have no this issue. MSFS v.1.36.2.0
Pop-up should work on any window - PFD, ND, CDU screens, even on MCP and radio panels.

Thanks again Rodolf, your tip was great. It's working now.  :)