The Side View doorhanger does not render accordingly when the browser's Dark Theme is enabled on latest Nightly

[Softvision-CristinaBadescu]

[Affected versions]:

• Nightly 63.0a1, Build ID: 20180708220048
• Side View 0.4.3

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Prerequisites]:

• Have the Dark Theme enabled.

[Steps to reproduce]:

1. Open the Firefox browser with the profile from prerequisites.
2. Navigate to the "https://testpilot.firefox.com/experiments/side-view" page and install the Side View experiment.
3. Click the Side View toolbar button and observe the doorhanger.

[Expected result]:

• The doorhanger is rendered respecting the dark theme: light gray text on dark background.

[Actual result]:

• The doorhanger is rendered to the default theme: black text on light background.

[Regression]: This issue is not reproducible using the latest Firefox Release 61.0.1 or Firefox Beta 62.0b6. Considering this, I've managed to find a regression window using the Mozregression tool. Here are the results: Last good revision: 1cb2bf41a61f110778b8d9176cfaa9ce348334f4 First bad revision: a8466a8972cd9ea621896da0f2bafc4472f2dfed Pushlog: https://goo.gl/chKjDQ From the pushlog, it looks like Bug 1472286 has caused this issue.

[Notes]:

• Here is a screen screen recording with this issue:

[johngruen]

@nt1m are you changing around theme API properties in Nightly RN?

[nt1m]

@johngruen The dark theme ID was changed from "firefox-compact-dark@mozilla.org@personas.mozilla.org" to "firefox-compact-dark@mozilla.org", so this check no longer works.

Generally, you should avoid relying on internal IDs to do theme checks.

[tiansh]

For users using Windows 10 who enabled "Settings - Colors - More options - Choose your default app mode - Dark" in system, the default theme act as dark mode. This behavior is introduced by bug 1368808. When trying to test which theme is enabled, you would just got "Default" instead of "Dark".

[intika]

Same issue here but for me it's worst the background is while and the text is white grey... i am under linux official ffox release 63.0.3 default theme (dark layer)... even when changing to white theme the popup stays the same white/white-grey text and almost unreadable it could be related to gtk but firefox work correctly it's just the extension menu... i don't have the problem in multi-account ext. even if the pop up should follow the rest and have a dark background

by the way i did not change the colors settings

a nice solution would be just a dark/white theme like the note ext