Hey. Is there an existing NES Palette editor for MiSTer? I'm guessing that the palette files were generated with a hex editor - at least I couldn't find an existing app (that works) in my research.
Since I couldn't find one, I created one in C# and .NET with WinUI3. Windows app, of course. I'm a C# dev by day, and wanted to try WinUI3 for something outside of production. Unfortunately, WinUI hasn't worked out so well; imagine that! My app currently works when ran from Visual Studio, but crashes outside of it when loading a palette file.
Would this be useful to anyone? I have a link to the project on my github here if anyone wants to try it. NOTE again: there is no binary release currently as it crashes unless ran within Visual Studio.
I've spent hours trying to debug my issue with no luck, and I'm not letting perfect be the enemy of... okay? 
I really wanted to shadow drop something cool that works.
I know there are plenty of palettes already so this app is probably more of a toy at this point, but I have created some ridiculous palettes with it that I had fun messing with. They're in the Samples folder of the source code if you'd like to try them.
If anyone is an expert in WinUI3 (/s) and wants to take a look, or even fix it and send a pull request, that would be awesome. It's MIT licensed and I have no issue with people forking it or doing whatever. Otherwise, I'll try to find a solution on my own schedule.