When using the Keep and Remove with the Scribble tool, I often would like to start anew with all red and green scribbles. A "Clear" button would be useful, and there's plenty of room to put one up in the Scribble's Options bar.
I noticed you were posting a lot of great suggestions and ideas on how to improve the app. We are definitely interested in collecting this info but I was wondering if you could post them as ideas rather than questions. The current process is to post each idea as a separate idea thread and other community members vote on the idea if they would like to see it added also and can add comments. The developers look at the list of idea threads and which ones are getting the most votes and consider these when adding features or changes into futures releases.