A user writes: "I was looking for the save button [meaning the bookmark icon] and it doesn't appear unless there are changes in the filter. That makes it harder for new users to discover that it exists. I would advocate to show the icon grayed out instead of letting it completely disappear."
This is an easy change to make and I agree that it would improve discoverability of the feature. The disabled state should follow the standard widget colors (the "IconWidget (disabled)" section in the widget demo has an example).
To make the functionality more clear, let's include a tooltip in the grayed out state only, as follows:
- These filters are already saved.