I have two monitors. One is 1920x1080 100%, the other is 2160x1440 150%.
Task bar is on the 150% monitor.
If I put a Lister on the 100% monitor, and click the Directory Opus tray icon in the 150% monitor, it goes a bit odd - see pic!
As far as we can tell, that's a bug in Windows itself. One of many with mixed DPIs.
Windows sometimes applies the DPI scaling of one monitor for windows opened on another. It appears to happen sometimes if an app has an active window on one monitor but then opens a window on a different monitor, and the monitors have different DPIs. it's definitely an OS bug as the active window is not specified or really relevant when the new window opens, and the monitor/position is specified and relevant; so the OS should know which DPI to use (the one for the monitor the window is appearing on) but gets confused and picks the wrong one.
Mixed DPI in Windows 10 isn't ready for use yet, IMO. High DPI works very well (although still has one or two minor cosmetic bugs) but mixed DPI is still new and quite broken.
OK great, many thanks!