i connected the external monitor to the pluggable 3900 and found the cursor display on both screens. but the external monitor only shows a backgroung no window content
Thanks for posting, and I’d be happy to help you with your docking station.
Based on your description it sounds like the dock is working as expected. Typically when you add a second monitor to a Windows system it defaults to something called ‘Extended Mode’. Just as the name implies, it means that this monitor is an extension of your desktop and that you see the Windows background image on it indicates that it’s working as intended, but you won’t see any icons or applications on that monitor until you move them there manually.
We made a short video that provides an introduction to how multiple monitors work here: https://youtu.be/0jDgITDfZAs
We also made a short video to explain a common problem with how things move back and forth here: https://youtu.be/kajujwoPsT8
Please let me know if that information helps!