Configuration
- Windows 10 client
- High DPI screen (3840x2160). Using Windows 10 scaling to 200%
- Two additional external NORMAL-DPI screens 1920x1080
- Windows 10 RDP (version 10.0.10586)
- Connection target: Windows Server 2008R2
Problem
DPI scaling in Windows 10 is way better than it has been but with room for improvement. Connecting to other machines (in this case Windows Server 2008R2 SP1):
1) On the high DPI screen, full screen. Displays at the full resolution, 100% scaling so everything is tiny and it's close to unusable.
2) On the normal DPI screen, full screen. Displays at the full resolution for the monitor hardware (1920x1080) everything is the correct size except the mouse pointer is TINY. What's worse, the vertical I-beam text cursor doesn't appear at all (I suspect because an I-beam bitmap for the cursor set that small doesn't exist). Editing any kind of text is unusable because you lose the mouse pointer when hovering over those areas.
Solution
Instead use Remote Desktop Connection Manager (RDCM) 2.7 but with "Disable display scaling on high DPI settings" UNCHECKED. Checking it will produce the same results as with RDP.
This time:
1) On the high DPI screen, full screen. Displays at the full resolution, but with correct 200% scaling so everything looks as expected. One minor issue is that if that screen has a windows toolbar, "full" screen doesn't quite fit and we end up with scrollbars. This can be fixed by auto hiding or removing the task bar from that screen.
2) On the normal DPI screen, full screen. Displays at the full resolution for the monitor hardware (1920x1080) everything is the correct size but this time the mouse pointers are the expected "normal" size. Works completely as expected.
Comments
The RDP client has come a long way recently but still has a way to go until it properly supports the scenario as mentioned above. I haven't tried but believe that connecting to newer windows OSes is fine.