Starting with After Effects (Beta) version 18.0, the user interface, especially on Windows, can be placed on or moved between monitors set to different display scales/resolutions (in the Display settings in Windows 10 or the Displays control panel in macOS), and look correct and sharper without having to relaunch the app.
In addition to this change, the following related bugs have been addressed:
Eyedropper was not picking the correct color when sampling from a different monitor.
The borders of windows and dialog boxes were not drawing on all sides when the display scale changed.
The contents of the About screen were not appearing in the correct place when the app window was on an external monitor set to a display scale different than the primary monitor.
REQUESTS FOR TESTING:
If you use a multi-monitor setup, especially when they're set to different display scales or resolutions, try moving windows and dialog boxes between monitors to make sure they appear properly (i.e., their contents are not too small, too large, or are blurrier than expected for the monitor). We're especially interested if you use or develop extensions (CEP) or scripts (ScriptUI).
Let us know if you encounter any issues with their user interfaces looking incorrect as compared to the latest released (non-Beta) version of After Effects, especially when moved between monitors of different display scales or when on a single monitor when the display scale is changed.
Also, on Windows, if you previously overrode the high DPI scaling behavior of the After Effects app, please disable it (i.e., use the default setting) to test this improved multi-monitor scale support.
Some secondary windows for third-party CEP extensions might not appear at the correct scale after moving between monitors.
When some docked CEP panels are docked in a workspace, and the After Effects app window is dragged between monitors, the CEP panel's contents might not appear at the correct scale. This issue does not occur if the CEP panel is undocked and moved between monitors.
Workaround for these issues: Resize the panel to refresh its contents.
(Use this Beta forum thread to discuss this feature and share your feedback with the After Effects team and other Beta users. If you encounter a bug while using this feature, let us know by posting a reply here or choosing "Report a bug" from the "Provide feedback" icon in the top-right corner of the app.)