I want to add length to a picture without stretching it, so I want to copy a sliver of it and add it onto the end. I figured out how to increase the width of the canvas size, but when I drag my selection to cover the now empty sliver of the canvas, it starts disappearing as it slips onto the checkered portion ("alpha channel"). How do I make it where it will show up on the checkerboard part so I can position it correctly and then fuse it (which I don't know how to do either so might as well ask too)
2. Make a selection of the right hand edge (see the selection border)
3a. Copy the selected area
3b. Paste. Right Click on the Floating Selection and "To New Layer"
3c. Use the Flip Tool to flip this new layer horizontally
3d. Move so that the edges line up with no gap.
4. Use the Scale Tool to stretch the new layer (Keep Aspect must be unchecked)
If it is a small amount you wish to add, you could try a plugin I created - plugin-uncrop-side.py
It works well for additions up to about 5% and it can be run more than once to increase the size.
