[Feature request] Add ability to zap elements of iframes

[cD1rtX3]

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.

I tried to reproduce the issue when...

• uBO is the only extension.
• uBO uses default lists and settings.
• using a new, unmodified browser profile.

Description

Often, a problematic element is in an embedded page, rather than the main page. I can delete the element inside the frame with DevTools, so I should be able to zap it in uBO.

A specific URL where the issue occurs.

https://www.w3schools.com/html/tryit.asp?filename=tryhtml_iframe_target

Steps to Reproduce

0. Be on a page with an iframe.
1. Try to zap an element within the iframe.

Expected behavior

The zapper should highlight the element I want within the iframe.

Actual behavior

The zapper highlights the entire frame.

uBO version

1.68.0

Browser name and version

Microsoft Edge 143.0.3650.139 (Official build) (64-bit)

Operating System and version

Ubuntu 24.04.3 LTS on Linux 6.8.0-90-generic

[gothic-bum]

Similar to: #2821

[freezer2022]

Somehow related indeed regarding the context menu entry, but originally most likely #3925 is an another duplicate of:

• Element picker works incorrectly on mail.com gorhill/uBlock#1744

it was fixed for Picker few years ago (resulting in a uBO's "Block element in frame" context menu), but not for Zapper, but it's caused by the same root reason: unability to drill into embedded frames.