UI scaling issue on Win10 desktop

[rkost]

Maybe a duplicate of #694 - sorry if so.

So this appears only to be a problem on windows 10 devices with more than one screen connected (no scroll bars whatsoever - By the way: this also happens to uBlock origin):

As one can see the plugin content is shown to big. Scrollbars are there for a fragment of a second and then disappear forever.

Setup:

• Windows 10 Pro 64bit (1709 currently but also earlier versions).
• Two monitors connected:
  1. 4k screen (scaling is set to 150%)
  2. 1080P screen (scaling is set to 100%)
• Firefox 57.0.2

Problem only occurs iff firefox is displayed on the second screen (the 1080p one). Everything works fine on the other one.

This issue does not exist when installing uMatrix in chrome so either firefox does a poor job rescaling plugins or there is something wrong with uMatrix.

[gorhill]

with more than one screen connected

Browser issue: https://bugzilla.mozilla.org/show_bug.cgi?id=1387340.

[Cerberus-tm]

Update (from the Mozilla bug above): this issue has been fixed, and the fix will be implemented in FF 58 (or 59).