Element zapper and picker do not work properly on CSP protected sites

[one-way-ticket]

Prerequisites

• [+] I verified that this is not a filter issue
  • Filter issues MUST be reported at filter issue tracker
• [+] This is not a support issue or a question
  • Support issues and questions are handled at /r/uBlockOrigin
• [+] I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • Your issue may already be reported.
• I tried to reproduce the issue when...
  • [+] uBlock Origin is the only extension
  • [+] uBlock Origin with default lists/settings
  • [+] using a new, unmodified browser profile
• [+] I am running the latest version of uBlock Origin
• [+ ] I checked the documentation to understand that the issue I report is not a normal behavior

Description

Open URL https://mpc-hc.org/
After clicking on the "zapper" or "picker" button, I see a broken pop-up interface.
Disabling all filters does not affect the problem.

A specific URL where the issue occurs

https://mpc-hc.org/

Steps to Reproduce

1. Clean install browser with new profile.
2. Clean install uBO legacy with default settings/filters.
3. Open URL https://mpc-hc.org/
4. Click on the uBO button on the browser toolbar and select "zapper" or "picker".

Expected behavior:

Ability to select a page elements.

Actual behavior:

Unable to select page elements. Pop-up interface is broken.

Your environment

• uBlock Origin version: 1.16.4.24
• Browser Name and version: Basilisk 2020.06.10, Serpent 2020.06.19 (fork of the Basilisk), Pale Moon 28.11.0, MyPal 28.11.0 (fork of the Pale Moon).
• Operating System and version: Win 7 Pro x32 SP1, Win XP Pro x32 SP3.

[gwarser]

gorhill/uBlock#2240

[JustOff]

Well, the problem is that the original fix does not help. This requires further investigation.

[JustOff]

It looks like nothing can be fixed on the extension side until the browser implements bug #1415352 (FF59+).

[pasha-zzz]

FF59+

But bug is present even on FF 52 f.e.

nothing can be fixed on the extension side

And Scriplet Doctor cannt fix too?

[dartraiden]

But bug is present even on FF 52 f.e.

Bug was fixed in FF59, not introduced in 59.