Filter for comments and category. Option to combine the filters with AND or OR. If one of the filters is empty, only the other is used. If both are empty, no filtering takes place.
Changing any of the four widgets (category list, AND-OR-button, comment field, regex-checkbox) triggers the filtering.

TODO: make the placeholder in the category drop down non-selectable.
Filter objects by category and/or comment. Changing the category, the and/or-button, the comment filter or the regex checkbox triggers the filtering.

TODO: make the placeholder in the category drop down non-selectable.