Enlarging canvas to hold a photo caption
I like to create a photo image to print on 8.5x11 inch paper (roughly A3). I want to print a test image, then go back into GIMP and add a little space across the bottom of the photo to include a caption which holds just a few words, incl a copyright notice.
This was easy to do in .psd and I think I've also done this in GIMP, but now cannot remember how. I tried enlarging the "canvas", which creates the strip across the bottom OK, but it is transparent. How can I make it white? Bucket fill doesn't work. Creating an rectangular selection doesn't work. Just starting the text tool doesn't work. I need a white background on which I use the text tool to write my caption. Maybe I can create the space by enlarging the existing image content rather than enlarging the canvas, but how? Or if I enlarge the underlying canvas, how can I paint it white and then use the text tool?
Thousands of other photographers must know how to do this, please tell me the easiest way in GIMP.
Thanks!
bluejay41