[Windows] The vertical scrollbar is wrongly displayed in the "Intro panel"

[SoftVision-EmilPasca]

[Notes]:

• This issue is not reproducible on Mac or Linux.

[Affected versions]:

• Firefox Beta (59.0b14)

[Affected Platforms]:

• All Windows

[Prerequisites]:

• Have the latest Tracking Protection Messaging .xpi installed (v.1.0.2)

[Steps to reproduce]:

• Open the browser with the profile from prerequisites.
• Navigate on a webpage with blocked resources (eg. www.cnn.com).
• Observe the Intro panel.

[Expected result]:

• The Intro panel doesn't display any scrollbar.

[Actual result]:

• The Intro panel displays a vertical scrollbar.

[Additional Notes]:

• The issue is reproducible only on "private" branch.
• Attached a screen recording of the issue:

[biancadanforth]

Thanks Emil for finding this. This is the result of a workaround I did on Windows for #161 . I did a thing you should never do: explicitly specify the height of the panel. I have an idea for how I can avoid doing that.

[biancadanforth]

There will be new behavior per this comment that will fix this issue; patch forthcoming.

[SoftVision-EmilPasca]

This issue is no longer reproducible with the latest Tracking Protection Messaging .xpi installed (v.1.0.5), retested on Windows 10 x64 with Unbranded Beta 59.0b14.