[mv3] Bring back element picker in a limited form

[gorhill]

Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality in the uAssets issue tracker.
• This is NOT a YouTube, Facebook or Twitch report. These sites MUST be reported by clicking their respective links.
• This is not a support issue or a question. For support, questions, or help, visit /r/uBlockOrigin.
• I performed a cursory search of the issue tracker to avoid opening a duplicate issue.
• The issue is not present after disabling uBO in the browser.
• I checked the documentation to understand that the issue I am reporting is not normal behavior.

Description

Long term: Bring back element picker in some form, only to cosmetically filter (we can specify a string when programmatically injecting CSS, unlike when injecting JS), and only those who would use such custom filters would cause uBOL's service worker to wake up for the sites for which there are custom filters, thus not undermining uBOL's efficiency and reliability for built-in filter lists.

[stephenhawk8054]

Would domain wildcard or domain regex be supported in element picker? I guess regex is not feasible for the service worker's efficiency?

[gorhill]

Would domain wildcard or domain regex be supported in element picker?

It's not currently supported by uBO's element picker, so I don't see that uBO Lite's element picker should support these.

Domain wildcard is currently supported when declared in filter lists though. Regex-based domains could be supported as well, the matching is made in content scripts, not the service worker, and I didn't add support right away because I want to investigate more the consequences for content scripts, especially for the the fact that a content script requiring a regex-matching would need to be unconditionally injected in all sites (with default set to optimal or complete). Currently there is a heuristic to minimize injecting in all sites whenever possible but I have to investigate more what is currently happening -- probably most cosmetic-related content scripts are already injected everywhere.

[ilove-adblock]

Why not first allow users to paste cosmetic filters (from their previous uBo installation) and then see for the element picker ?

[ale5000-git]

Is this the same as "My Filters" of uBlock Origin or did I misunderstood?

[jakeyounglol]

Is this the same as "My Filters" of uBlock Origin or did I misunderstood?

yes