Put a thumb somewhere. Put the buttons somewhere. Watch how far the hand has to travel.
Drop or paste an image anywhere on this page to use your own screen. Files are decoded in this tab only — nothing is uploaded, stored, or remembered after you close it.
Drag the amber puck to move the thumb base. Drag any ring to move a target. With a target focused, arrow keys nudge it (hold Shift for coarse), Delete removes it.