Possible regression bug: Preview of CSS 'style' filters no longer works

[yourduskquibbles]

When using the Element Picker tool, clicking preview on filters that contain the CSS modifying :style(foo !important;) tag no longer seems to work. Wondering if this is somehow related to the fix for #3159?

One or more specific URLs where the issue occurs

https://digg.com/

Screenshot in which the issue can be seen

Can post animated gif if needed.

Steps for anyone to reproduce the issue

1. Navigate to 'https://digg.com'
2. Use the Element picker tool to click on the header and add the following filter
   ###js--digg-header:style(position: absolute !important;)
3. Click 'Preview' and scroll down the page, the header SHOULD stay at the top and not be a floating header but in the newest versions of uBlock the preview behavior seems to have stopped working.
4. In order to confirm this is a valid filter that will pin the header to the top of the screen, click 'Create' and reload the page and observe the correct behavior of the header staying at the top of the screen.
5. In previous versions of uBlock you used to be able to click 'Preview' and see the impact before having to create the filter.
6. Is this possibly related to 374e157 which fixed :style filters incorrectly shown in logger #3159?

Your settings

Tested on:

• Windows 7
• uBlock Origin dev build 1.14.19.8 on Chrome 62.0.3202.94 (Official Build) (64-bit) AND 1.14.19.b8 on Firefox 57

Your filter lists

Default lists

Your custom filters (if any)

None

Thank you for looking into this, your plugin is awesome! I have a number of people using your plugin and my Annoyances filter list to unsuck the web, one user at a time :)

[gorhill]

Unable to reproduce, the header stays at the top with or without the filter. Using only default settings/lists.

[yourduskquibbles]

Hi @gorhill, thanks for taking a look apologies if my first example did not work.

Can you try reproducing with the following steps on a different site?

1. Navigate to https://www.redditgifts.com/exchanges/manage/#/exchange/secret-santa-2017/
2. Use the Element picker tool to click on the "floating" header and add the following filter ##.js-header-main.header-main:style(position: absolute !important;)
3. Click 'Preview' and scroll down the page, the header under previous versions SHOULD be PINNED to stay at the top and not be a "floating" header but in the newest versions of uBlock the preview behavior seems to have stopped working and the header remains a floating header while scrolling down after clicking 'Preview'.
4. In order to confirm this is a valid filter that will pin the header to the top of the screen, click 'Create' and reload the page (shift + f5) and observe the correct behavior of the header now being 'pinned' to stay at the top of the screen which you were unable to see this style change using 'Preview'.
5. In previous versions of uBlock you used to be able to click 'Preview' and see the impact before having to create the filter.

[gorhill]

Ok, I understand what you mean: with the filter, the top banner should scroll with the rest of the page, not being pinned in the viewport. I will investigate.

[gorhill]

The regression was introduced in fix to #2984: 6112a68#diff-3b15596213ed9ba37fb5b8bb1402a6c2L811.

[gorhill]

Good catch, thanks for reporting.

[yourduskquibbles]

Thank you @gorhill for the quick fix and all you do for the community!