I am able to use the scroll wheel to zoom in and out, until I click in the Brush Presets docker. After that point, using the scroll wheel will scroll the Brush Presets docker up and down, whether or not it is the active docker. Closing the Brush Presets docker does not release the scroll wheel.
Thanks for your report! Do you know which version of Qt is installed on your computer? If you are using Qt 5.7 (or presumably newer), then you are probably experiencing bug 364850.
I'm pretty sure it's that problem, since grean reported using packages. *** This bug has been marked as a duplicate of bug 364850 ***