[Affected versions]:

• Firefox Latest Nightly 66.0a1
• Firefox Beta 65.0b9
• Firefox Release 64.0

[Affected platforms]:

• Win 7 x64
• Win 10 x64

[Steps to reproduce]:

1. Reach https://www.bing.com/maps.
2. Click on the traffic button.
3. Select the aerial mode.

[Expected result]:

• No element obstructs the map.

[Actual result]:

• There is a scroll bar in the middle of the screen.

[Regression range]:

• Will investigate as soon as possible.

This is basically a site bug.

They explicitly ask for this scrollbar -- they style the element in question with:

.noScroll {
   overflow-y: scroll;
}

And then in Chrome and Edge, they hide the scrollbar by setting a negative "margin-right". It looks like this:

<div class="panelWrapper multi left noScroll" style="margin-right: -17px;">

This ends up clipping the scrollbar, because this element's parent has overflow:hidden, so it hides the negative-margin-area on its child (which is the child's scrollbar area).

But in Firefox, they give this element "margin-right: 0px". On Linux, that's fine because scroll tracks are transparent (and maybe they're trying to use 0px for that "we figured out that scroll tracks are transparent" scenario?) But on Windows, scroll tracks are not transparent, so they need to give us a similar margin-right bump that they're giving to Chrome in order to hide the scrollbar.

I can also reproduce the issue on Chrome dev73.0.3642.0 Windows10 sometimes.

Adam, can we reach out to microsoft on this one please?

Reaching out to Microsoft via partner mailing list.

They passed this report along to the right team internally.

See bug 1547409. Moving webcompat whiteboard tags to keywords.

The traffic pane has since been redesigned. It is now full-height and shows no scrollbar.