I am running Hatari on a new Surface Pro with a high DPI display (2736 x 1824, 266DPI) and am having a few scaling issues.
1) The mouse cursor in the Hatari F12 screen is very tiny, not scaled with screen resolution. The Atari mouse cursor is correct (though it tracks my mouse poorly)
2) When I go fullscreen with "Keep resolution", I only end up seeing about 1/4 of the Atari screen, like it zooms in too much. This seems to happen when I run as a Falcon or with an extended VDI graphics screen (in this case, running as a MegaSTE) -- If I run a MegaSTE and use ST resolutions, fullscreen seems to work fine.