(05-19-2023, 10:24 AM)prandus Wrote: Is it possible to copy the outline of a selection from one layer to another?
I say the outline, and not the content.
If you mean by outline, the 'marching ants', (aka marquee) you get having made a selection, then that applies to all layers.
All you need do is make the required layer active by clicking on it in the layers dialogue, then copy / paste / cut / fill whatever you need to do on that layer.
For future use you can save a selection: Select -> Save to Channel and restore at a later date from the Channels dock. see: https://docs.gimp.org/en/gimp-channel-dialog.html and https://docs.gimp.org/en/gimp-channel-di...annel-mask
When you Save an image as a Gimp .xcf file that channel information is kept and also an active selection if there is one.