You know it would be a good idea to add in a eraser tool by itself.
So that way you can put the other tools such as "Eraser_Pencil", "Eraser_Rectangle" and
"Eraser_Floodfill" could be in it and so people can use a regular eraser when it comes to getting soft adjustable eraser functions. So the user would 1) Not have the difficulty to making a mistake and have to hold or press (multiple times) on the "Ctrl+z" command.
2) Would easily find all eraser type tools in one eraser category without needing to switch to multiple
tools just to find the right one. 3) For organization purposes and I hope you know all the other necessary
needs for an adjustable eraser not just pixels, rectangular shapes and flood-fill types.

There are pros and cons as always. But if you prefer this your way, you can reconfigure the toolbar with drawing tools. Right-click on it, open the config window, resize it a bit and then edit the loooooong line with tool names. [] means those tools are in a group.