Created attachment 175906 [details]
^ Two screenshot in a single picture (and a Quiz to underline the issue)

Hi,

How to reproduce:
In the Brush Presets docker, press the Storage Resource icon (the most top right icon, an 'archive' icon). This one will bring up a drop-down menu with a list of the bundles installed on your system. They can be enabled or disabled by clicking on the item. Click on them.

The problem:
It is really difficult to know what is activated and what is not. 
- Is it when a button is "pressed" that it is activated? 
- Is it when the frame is around the item that it is activated? 
The UI feedback is confusing...
If you have any doubts, take a look at the image in the attachment, I made a quiz between two screenshots.

Context at Capitole du Libre workshop:
Yesterday, at my Krita workshop at the Capitole du Libre, a user disabled it by simply exploring the interface without noticing. And to add insult to injury, when another user and I tried to troubleshoot her installation, we blamed a Linux Mint/Flatpak problem, presumably with not enough permissions to load the brush bundle due to the container thing (and also unsupported Flatpak)... As we could not find the problem, she had to do the workshop with only the 6 brushes of the RGBa bundle available in her interface, also believing (and I feel bad for this) that her installation was wrong. This morning I realized that this menu could be the culprit, and when I tested the user feedback of the button, it made sense.

Wish:
I think a tiny checkbox in front of the item would disambiguate this activated/deactivated state. This is just a suggestion.
Thank you!