Summary: Creating child filters, which inherit filtering from parent filters.
Motivation: Allow users to create personalised filter hierarchies with easy maintenance. For instance, a user might wish to maintain several filters for different circumstances (e.g. a SFW filter to only browse wholesome pictures, and a NSFW filter which they’d only use specifically when they want to view explicit content), while also having certain things always filtered (e.g. some fetish, or a particular artist).
Currently, to adjust their “global” preferences (e.g. if they find a new artist or tag they wish to permanently hide, or if they wish to unhide something they previously hid), they have to edit every individual filter they use regularly. If filters could be “parented” to another filter, they could create a single template filter hiding everything they never want to see, and then create sub-filters or child filters for every individual view they want to have. (Or in the example above, they could simply parent the SFW filter to the NSFW one, assuming the SFW one was strictly more restrictive than the NSFW one). Then, they’d only need to change the single parent filter to update their view when using any of their custom filters.
If this feature was extended, it could even be used to allowed to compose complicated views at will. E.g. one could create a “no anthro” filter, a “no EqG” filter, and a “allow whitelisted artists” filter, and then compose them to create any combination, e.g. “show me neither anthro nor eqg”, “hide anthro except for the artists I’ve whitelisted”, etc.