Found in

• Nightly 111.0a1

Affected versions

• Nightly 111.0a1
• Firefox 102.7.0esr
• Firefox 110.0b9
• Firefox 109.0.1

Tested platforms

• Affected platforms: Windows 19, Ubuntu 22.04, macOS 13
• Unaffected platforms: none

Steps to reproduce

1. Go to www.instagram.com and log in using a valid account
2. Click on the "Create" from the left-menu
3. Close the window by clicking outside of it
4. Move the pointer of the mouse up and down on the page( without holding down the left mouse button)

Expected result

• The "Create new post" window should be closed and no text should be selected on the page.

Actual result

• The "Create new post" window is closed and the text is selected on the page.

Regression range

• Not a recent regression because I was able to reproduce this issue in builds going back as far as 86.0a1 .

Additional notes

• The issue is not reproduceable in Google Chrome.
• The issue is not reproduceable when closing the "Create new post" window using the corresponding X button.

I can no longer reproduce this issue in the latest Firefox 121.0.1 and Nightly 124.0a1 versions on Windows10 x64.
Marking this as WORKSFORME.

Verified this issue and could not reproduce it on Firefox versions 122 and 124

Tested with:

Browser / Version: Firefox Release 122.0 (64-bit)/ Firefox Nightly 124.0a1 (2024-01-25) (64-bit)
Operating System: Windows 10 PRO x64