A new tab cannot be opened using keyboard shortcuts on Mac and Linux if a dropdown menu is already open

[Softvision-PatriciuPop]

[Affected Versions]:

• Firefox Release 67.0.1
• Firefox Beta 68.0.1
• Firefox Nightly 69.0a1

[Affected Platforms]

• All Mac
• All Linux

[Perquisites]

• Logged in with your LDAP account.

[Steps to reproduce]:

1. Open the browser with the profile from prerequisites.
2. Navigate to the https://stage.experimenter.nonprod.dataops.mozgcp.net/ website.
3. Click on the "Most Recently Updated" dropdown menu.
4. Press the "Cmd+T" ("Ctrl+T" on Linux) keyboard combination on the keyboard and observe the behavior.

[Expected results]:

• A new tab is opened and focused.

[Actual results]:

• Nothing happens.

[Notes]:

• The issues is reproducible using all the dropdown menus from the "Sort Experiments" and "Filter Experiments" sections.
• Attached a screen recording of the issue: here.

[Softvision-PatriciuPop]

It appears that this is a Firefox issue that I have been able to reproduce on other websites that have dropdowns that use the "select" element. For testing I have used this site . I will log a new bugzilla issue and post another comment.

[Softvision-PatriciuPop]

Here is the issue logged in bugzilla: link

[shell1]

closing as this isn't a blocker for our usability. we'll inherit if Fx fixes, but not concerned.