I’m currently using Krita 4.1.7 on Mojave. Not sure if this problem is universal, but the dialog window is crippled, and floating windows can’t be resized. Which means at higher monitor resolution, you will have a hard time with color picker (for example).
NOTE: A simple fix for the dialog window being crippled (only showing half) on macOS as of this writing is to make sure you open it. And let it remain open at all times. Even when you’re not using the pop palette. Relaunch Krita (exit/open) and the app will automatically adjust the dialog. Don’t close that dialog via the Pop Palette. You’ll have to repeat this step if you do.