Prerequisites

• I performed a cursory search of the issue tracker to avoid opening a duplicate issue
  • Your issue may already be reported.
  • I also searched the existing issues at https://github.com/gorhill/uMatrix/issues
• This is not a support issue or a question
  • Support issues and questions are handled at /r/uMatrix
• I tried to reproduce the issue when...
  • uMatrix is the only extension
  • uMatrix with default lists/settings
  • using a new, unmodified browser profile
• I am running the latest version of uMatrix
• I checked the documentation to understand that the issue I report is not a normal behavior
• I used the logger to rule out that the issue is caused by my ruleset

Description

Hi.

I disable dom Intersection Observer API for many years. For privacy and security reason of course. I have never had a problem with this. Until now. As it turned out, if the api is disabled uMatrix 1.4.1bx does not work either.

Steps to Reproduce

1. Fresh install Firefox browser (any version).
2. Install any dev version uMatrix 1.4.1
3. Open about:config
4. Find string "dom.IntersectionObserver.enabled"
5. Change from true to false.
6. Restart browser.
7. Try open popup on uMatrix badge

Ruleset

Default ruleset. Nothing has changed.

Supporting evidence

uMatrix 1.4.0 and lower not have this issue. I think this is somehow connected with DOMRect. But I'm not sure.

Your environment

• uMatrix version: 1.4.1bx
• Browser Name and version: Firefox 73.0.1
• Operating System and version: Windows 10