Can you port it to Windows? Windows has, from what I can tell, no decent screenshotting + annotating tool that compares with Skitch or any of the Mac alternatives.

Lightshot comes the closest to a decent, light, free alternative but it's still not ideal.

The built in Windows tool is nice (win + shift + S) but there's no arrows, it's a faff to get straight lines and it's just up to the quality of the OSX tools.

I started making one but like all side projects it just sits there waiting for that elusive "free time".

Thanks