Food for thought: Category input using "dasher" input method.

[ubacher]

Have you tried the program "dasher" which allows text input by just small movements with the mouse?
I can recommend downloading and installing it just to try. (Wiki page, free, uncomplicated  program)

What just occurred to me was that this would possibly be a good method for category entry.
Assuming of course that it could be adapted and that one has a reasonably hierarchical category tree.
Food for thought!

[Carlo Didier]

Interesting system. Probably a good thing for people with disabilities.
Personally, I always found that predictive stuff (like on smartphone virtual keyboards) is more annoying than useful, but that is mostly because they never support my native language ...

[Mario]

There are maybe a dozen methods to assign files to categories in IMatch already, from Category View to Favorites and the various methods in the Category Panel.

I have not looked (no time) at the program you mentioned so I cannot comment of assigned files to categories by small mouse movements will improve the workflow for more than a handful of users.

I can assign dozens of categories to thousands of files with a few mouse-clicks in my Favorites Panel, triggering entire splasher sequences with a click or an <F3> shortcut. Maybe you are not utilizing all the features for category assignments already in IMatch?