How to reset or change behaviour of mouse cursor in impoly/imroi ?

I have question concerning reset of interactive behavior of mouse. When I click on button and activate mouse to create a ROI on the image. But user did it by mistake and want to select different option and then user click on listbox and once more on button ROI. How can I reset ( option impoly with cross like this : +)? How to reset interactive behavior of mause ?

I would appreciate any help or hint.