Prerequisites

• I verified that this is not a filter list issue. Report any issues with filter lists or broken website functionality by using the chat icon in the popup panel.
• 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 Lite in the browser.

I tried to reproduce the issue when...

• uBO Lite is the only extension.
• using a new, unmodified browser profile.

Description

Two separate issues here:

First issue:

uBOL's picker can't pick inside shadow DOM, which is kinda expected.
If we paste a selector contained in shadow DOM, the counter show 0, there is no highlight and [Create[ can't be clicked. This is expected as well.

However... Pressing [Preview[ works. It actually hides the element inside of shadow DOM.

Doesn't that mean it should be possible to enable filter creation too (even if the counter and highlighter don't work)?

Second issue:

If all filter lists are disabled (or just LAN list enabled - so likely when no cosmetic filters are present), which I know is not an expected use*... If I paste this into picker:

shreddit-post:shadow(shreddit-post-share-button)

It will show highlight, it will count matches, the [Create] button will be available and pressing it will add a filter, but the filter won't work. Also pressing [Preview] will also not hide the element even though it's selected by the highlight.

* I mainly have it set that way for testing purposes. uBOL's picker is useful on mobile but I don't want filter conflict vs uBO.

A specific URL where the issue occurs.

reddit.com/r/uBlockOrigin

Steps to Reproduce

1. Visit reddit.com/r/uBlockOrigin.

2. Open uBOL's picker.

3. Paste shreddit-post-share-button

4. Observe no selection or matches.

5. Click [Preview] to see the element hidden.

6. Disable all filter lists.

7. Refresh the reddit page.

8. Open picker again.

9. Paste shreddit-post:shadow(shreddit-post-share-button)

10. Observe counter and highlighter working, [Preview] failing.

11. Click [Create] and observe no change.

12. Refresh the page, same result.

13. Add at least one filter list (not the LAN one).

14. Refresh reddit and see the filter now working.

Expected behavior

1. Allow creating filters for selectors inside shadow DOM (since [Preview] works).
2. Let :shadow() operator work even if no filter lists are selected.

Actual behavior

As described above.

uBO Lite version

2025.1028.1744

Browser name and version

FF 144,0,2

Operating system and version

Linux