Yes, UI scaling is a little strange. I've noticed that it's best to start the theme with a 100% scale so that all the backend files initially create the files at 4K or whatever res you want. I actually lost some progress because I started a theme at 4k at 225% scaling and I was confused by why all the measurements were saying I was essentially at 900p res. I then realized that I needed to be at 100% scaling and you can't change it in the editor (the xaml text files won't show a difference if you change windows scaling) once it's initially created. So I forced to to be 3840x2160(4k) by editing on line in the xaml text file but this then threw off my entire theme because it got way smaller in the editor. So that's why I say start your themes at 100% scaling! What sets the resolution is that initially starting resolution and scaling of your theme. If later you then want to have the larger UI scaling for the editor and go to say 225% at 4k then the backend xaml files will still be 3840x2160 (4k) but sadly the measurement numbers will still be showing a lower res based on your scaling amount. So what I now do is this...once I set me theme initially at true 4k 100% scaling, I then set it back to 225% like i prefer for the ui scaling to be more readable. The pixel count of element sizes will still be off (but scaled proportionally so it still will stay in place with scaling changes) but the background xaml files will still say 3840x2160(4k). Once I have my theme loosely where I want want it I will then switch my dpi back 100% to do the precise movements and measurements. It's a bit of a pain but at least I understand it. Ideally, it should set the background xaml files and usable pixel measurements at 3840x2160 without it looking at your dpi scaling of windows. It should only be scaling the UI of the editor and not the theme element measurements. This is probably quite a hard issue to resolve I would imagine. I've also noticed that at times animations seem to be smoother at the initially set resolution and scaling. Sometimes when I change my scaling from 100% to 225% and test my theme the animations are a tiny bit laggy. But switching back to 100% they will be perfectly 60fps again. That doesn't always happen though so I'm still not sure what's up there. Maybe that's just me. On an unrelated note, just as a tip, I'll say this; If you are making custom art for your theme I have found it will only be fully clear if it's exported/created at 72ppi. At work I commonly export things at 300 dpi for print files. 72ppi is for web/screens generally. Anyway, I was drawing all these custom icons for my new theme (which I have yet to reveal) and was exporting them at 300ppi and when I tested them in my theme they were all super blurry! I was going crazy trying to figure out why. Then when I went back and reexported the files at 72ppi they were showing the real resolution and not a blurry mess. So I just scaled them up in Adobe Illustrator (they can scale because it's vector art) so that they'd still be pin sharp at 72ppi.