by showing redo panel. The A hotkey has "auto iteration" enabled by default, which calculates the number of times to run the filter using a heuristic based on vertex count. To make clear to the user what is going on the redo panel is now shown for the mask filter operator. NOTE: I discovered the source of the bug where sculpt operators' redo panels were greyed out. The name fed to SCULPT_undo_push_begin must match the operator name. I've added a comment in sculpt_intern explaining this.