creating a 1x1 brush: https://graphicdesign.stackexchange.com/questions/29932/how-to-create-a-one-pixel-pencil-brush-in-gimp resetting the window toolboxes: https://askubuntu.com/questions/461152/how-to-restore-the-default-toolbox-windows-in-gimp show rgb under the cursor: https://graphicdesign.stackexchange.com/questions/71248/how-to-display-current-colour-values-of-pixel-under-cursor-in-gimp creating a checkerboard https://www.youtube.com/watch?v=LuJLYRL47nU