Today's widely deployed painting applications use a linear undo model that allows users to backtrack previous operations in reverse chronological order. This undo model is not useful if the user has performed desired operations after undesired ones. Selective undo, in contrast, allows users to select specific operations in the past and only undo those, while keeping the remaining operations intact. Although selective undo has been widely explored in the context of text editing and object-oriented drawing, we explore selective undo for painting (bitmap) editing, which has received less attention and introduces many interesting user interface design challenges. Our system, called Aquamarine, explores the script model for selective undo, where selectively undone operations are skipped in the history, rather than the more explored inverse model, which puts an inverse of the selected operations at the end of the history. We discuss the design implications and show through two informal user studies that selective undo is usable and desirable