In a dual screen environment, dialog boxes in app window 2 can sometimes get stuck under the title bar of app window 2. In this case, the normal fix of choosing the Window menu and selecting the name of the window that's stuck, doesn't pull the window back down.
It may be possible to grab the window by placing the cursor as close to the bottom of the title bar as possible without touching it and then dragging down.If unable to make this happen, use this workaround.1. Go to Workspace>preferences and deselect "Open two application windows".2. Close and re-enter MicroStation.3. Open the same dialog as before. This time it will be stuck under the title bar of app window 1 (since it is the only window open). Now select the Wiindow drop down and choose the window that's stuck. It will reposition itself so the title bar can be accessed for moving.
https://communities.bentley.com/products/microstation/w/microstation__wiki/26156/how-to-recover-lost-or-hidden-tool-settings-dialog-box
https://communities.bentley.com/products/microstation/w/microstation__wiki/13452/troubleshooting-user-preferences-issues