How do I export a whole layer as an image?

I want to edit a whole layer as an image in another program.

What's the purpose ? Because you could try using the Print Screen button on the keyboard

Snapshot canvas, when triggered, will capture an image of the canvas. To download it you need to use the browser object - on Snapshot trigger, invoke the browser download (the url to download is the CanvasSnapshot in System, you will need to enter a file name including type (ie: LayoutName & ".png").

thanks