Popouts are blank when using Firefox

[wilmaier]

Describe the bug

When using Firefox, popped out widgets are shown blank.
This appears to coincide with the appui 5.0.5 update we made recently.
This issue does not appear for Chrome.

To Reproduce

It can be reproduced in the pineapple version deployed on QA-UKS but not localhost.

Case 1:

• Open any iModel in Firefox.
• Expand frontstages dropdown.
• Go to clash frontstage.
• Pop-out clash tests widget.

Case 2:

• Open any iModel in Firefox.
• Expand civil tools group.
• Pick 2 points cross-section tool.
• Section across geometry in the view.
• Pop-out cross-section widget.

Notice that popped-out widget is shown blank in a separate window. This seemed to got broken with AppUI 5.x upgrade, as popped-out widget work fine with AppUI 4.x.

Expected Behavior

Popped out widget should be rendered as it is in Chrome

Screenshots

##Clash detection widget popout:

##Civil cross-section widget popout:

Desktop (please complete the applicable information)

Firefox Browser - 135.0.1 (64-bit)

Additional context

No response