Steps to reproduce:

• Set the pref devtools.debugger.features.code-folding to true in about:config
• Open any page that has javascript running
• Open the debugger
• Move your mouse around the gutter area (where the line numbers are displayed)

Expected: the code folding arrows should behave normally.
Actual: the arrows are flickering when moving the cursor in the gutter and disappear when the mouse is not moving.

See the screencast: https://imgur.com/a/hbENqve

This was noticed by Karl while testing bug 1233332.
Tested in 68.0a1 (2019-05-13) (64-bit) on macOS 10.14.

Looking at this now; the flicker occurs because CodeMirror's HTML structure is a bit unfriendly. I'm looking at this now.

As a good compromise, I think we can stop trying to use JS + CSS tricks to only show upon hover, simply always show the gutter folding.

I can take a crack at this. It's been a while so I wouldn't mind starting with something smaller.

Sure. That'd be great. Fair warning, the css is tricky.

Hi everyone,

Is this still an issue? I wasn't able to reproduce this bug on my build of Nightly, built on 1/29/2020 and tested on 64-bit Windows 10. Here is a screencast of what I saw: https://streamable.com/glkh8

Best,
Abhi

I can't reproduce this anymore, closing.

Honza