Extend the tool tip for the "Undo" and "Redo" buttons
As a sloppy user, I sometimes hit a key I don't intend. Task Coach flashes and I wonder "What did I do? Did I delete something, or did the screen just refresh? Will undo fix an error, or get rid of my last intentional operation".
When I then try undo, it isn't always obvious what was undone. The change might be to something not displayed. I often hit undo several times until I can identify the operation performed, and then performe redo several times to get to a good state.
To address this issue, and give more information to users: Instead of just saying "Undo"/"Redo" in the tool tip, say "Undo Rename to 'x'". Include the operation and subject of the task (or part).