Close; -- but FlashDevelop is not a fork of MonoDevelop.

HaxeDevelop, however, is a fork of FlashDevelop, mostly a light rebranding given how much momentum has switched from Flash to Haxe. (Many people didn't know how many Haxe features FlashDevelop had, for instance).

Are you sure? It always looked like MonoDevelop (before it looked like Xamarin) to me... Guess I thought wrong then, but it's interesting both are in C# at least.