Click to place a dot. You can drag a dot around. Press c to clear. If the thumbnail breaks, press space to reset it. You MUST use Turbo Mode or it will be too slow and break. Laggy? Try Turbowarp: https://turbowarp.org/1255015019
Version 1.0.1 (8/2/26) fixes some bugs Version 1.1.0 (9/4/26) clear key is now 'c'