User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0

Steps to reproduce:

Open a message with multiple attachments
Click on the attachments pane header to expand it

Actual results:

Only the first attachment is visible
We have to scroll to show the other ones (only one line)

Expected results:

The pane should expand to show all attachments at once

This is most likely a regression.
The attachment pane used to open to the right height:
https://github.com/mozilla/releases-comm-central/blob/cb1bb087e06d4dc956f9736041013dfff680bfb1/mail/base/content/msgHdrView.js#L2599

Note that removing display: flex; from .attachmentList allows the pane to resize correctly but then only one attachment is shown by line.
https://github.com/mozilla/releases-comm-central/blob/e03ba5df0cd69185362ef5ad7d7aa37f87a8a3aa/mail/themes/shared/mail/attachmentList.css#L12

Hey Thomas, this worksforme on TB 102.2.1 (64-bit), Win10.
Toggling attachment pane open will show multiple rows of attachments (although it seems to expand to single row first and then recalculate to show more).

• Anything in error console (Ctrl+J)?
• Happens with ≡ > Help > Troubleshoot Mode…?

Exact same config here.
Reproduced in Troubleshoot Mode.
I tried it on a different computer with the same result.
Nothing in the error console.

Note that there are two ways to make this work:

• Enable mailnews.attachments.display.start_expanded (with a right click on the attachment bar)

Then either:

• Open the email in a new window (doesn't work in a tab).

Or

• If the message pane is shown, alternate between two messages with attachments (selecting one then the other one)

Similar - https://www.reddit.com/r/Thunderbird/comments/1193est/attachment_pane_too_short/.