For me, it was quite easy to get a decision:
- DELL Precision M3800 with 3200x1800 on Ultrabook TouchScreen + 1920x1200 on the second Monitor.
- Also the complete option "multiple Displays" is missing in taskbar properties.
- PLUS my System is automatically adjusting the window size/resolution when I move a window from the main screen to the second screen (which is quite practical having these different display sizes): Otherwise, elements which fit on one one Screen are too
large or too small on the other screen.
To get the "Multiple Displays menu" back, with Option "Show Taskbar on all Monitors" I have to
1) Switch the Display to the second Monitor only (Win + P), reboot
2) Turn of the INTEL(r) HD Graphics Utility which sits in the System Tray
3) and re-enable the Extended Screen. That's it. (not sure if the reboot is necessary)
BIG DISADVANTAGE: Automatic Window resizing gets lost, and additionally, all items on the high Resolution Display are very very small afterwards.
Re-enabling the INTEL Utility brings back automatic resize and lets the taskbar disappear again.
My decision: I leave it like it is - for now - and I will make up a call with INTEL rather than with Microsoft.
"The bad boy" seems to be the INTEL Utility - at least in my case.
Have fun. -jk-