How about changing the + icon at the cursor to a - icon when using ctrl to subtract selected geometries in the radius tool, so it shows that it actually does what is expected/something at all, or better yet make it so selected geometries remain clickable for un-selection to begin with instead of redundantly having to use an additional key? You know, instead of leaving the user furiously searching for this functionality and leaving him frustrated suspecting the only option being to delete the step and creating it anew?
Good lord this software is cumbersome...
