The Cut preview makes easier to define your Cut. So the next logical step was to add a preview for other tools, and it was done nicely: four tools (they are very similar also) are getting a preview dialog. Also the dialog that you can input the value have a slider to not be forced to switch to keyboard. This slider will go from 1/10 of the original value (by default 1) to 10 times the same value.
Also bug fixing was done and I've almost finished a tutorial about how to create a simple shape via a plugin: