2dguy As far as I'm aware, the 5.3.3 release (Feb 2018) is the most recent "stable" build of FlashDevelop.
neuronix For AS3 development, what's missing from the latest stable release of FlashDevelop? I'd still recommend that for AIR projects.
I'm using the nightly builds for my Haxe/OpenFL/Starling projects, as the release of Haxe 4 needed addressing. Certainly, a new release level build, or even release candidates would be nice. I'm not sure what the dev plan is for those sorts of things, or if there is one.