How are the 'units' (`what`) from the Tkinter canvas scrolling methods `xview(SCROLL, step, what)` and `yview(SCROLL, step, what)` defined? Is it defined in pixels? Is it possible to change it (for a slower scrolling for example)?

For a better context please see the code [here](https://stackoverflow.com/questions/6495317/python-tkinter-canvas-scrolling-with-mouse-position).

Thanks in advance.