Undocking level-d screen affects RC4?

I've done a search here on "undock+window", but didn't see anything.Today I tried using RC4.3 with level-d B763 (FSX, WinXP). I have two monitors, run in DualView. I undocked and moved the level-d throttle quadrant to my second monitor, while in VC mode. I found that I could not interact with the FSUIPC/RC4 dialogue to initiate ATC. Pressing the number keys did not invoke the usual "blinking" of the dialogue box, and while I got lots of ground chat, I couldn't go anywhere if I wanted ATC.Thanks, Bruce.