I was about to post the very same information you are asking about as a follow up entry.
Yes, that “blue square icon” that looks like a monitor is the “Plugable app icon” I was referring to above, correct?
The entry for my docking station is the “DisplayLink Manager” entry I presume, as I don’t see anything specific to the docking station labelled such (and it appears above: Check for Updates, Optimize for Video, Fit to TV, Advanced Configuration). In fact, this and the “Advanced Configuration” entries bring up the Win 7>Appearance and Personalization>Display>Screen Resolution screen that I can also access via Control Panel.
Assuming I am correct, and understand your instructions, I have already tried, and, as mentioned above, was about to report here…
When I switch to have it “show desktop only on 2” (the Dell monitor is defaulted to monitor #2), I get blank screens on both laptop (expected) and monitor (whoops!).
Of note, I’ve been reading on the net that one possible workaround is changing which monitor is primary. However, after changing from “duplicate these displays” to “show desktop only on 1” (my laptop screen), and then clicking on the monitor #2 graphic in the upper portion of the popup, the little check-box to “make this my main display” option is greyed out.
I’ve also tried the Function key that is design for quickly changing between modes when connecting to a projector (normally via the VGA port), but no setting there resolves this problem. I suspect it is just a fast-path interface to execute the same commands that the “DisplayLink Manager” path above does.
Looks like my laptop does not completely recognize that there is a separate monitor at the other end of the usb cable. It seems to just want to “split the signal” going to the laptop screen and send it thru the usb, but that is it.