Just "simply" port your native GUI application to a completely different platform and make sure everything works as intended. No biggie! At least donate a couple hundred dollars to the developer so he can afford to run a couple of Claudes before you start asking for things.
If you want an editor with the same core as Notepad++, but fewer batteries included and more extensibility, Textadept is worth a look.
When there are no trademark issues then there are no trademark issues to discuss.
But they haven't named it something else, so here we are talking about the trademark issues that this raises.
> One does not simply walk into Mordoras for the other commenters, i agree that all kinds of curmudgeon behavior from open source maintainers is valid. many personalities are valid. but it doesn't mean writing legal letters is a good idea, it's winning the battle to lose the war.
And someone using the Notepad++ brand without his consent isn't cool, as if something goes wrong, people might assume that the original Notepad++ author is behind it, tarnishing his reputation.
If he doesn't want to make a macOS version that's on him, other people can fork it and make their own versions if they want, just make it obvious it's not from the original dev.