New version of Thunderbird has limited the size of the drop-down that shows my open emails. How do I change it back to show all open ones?

There is an icon in the upper right corner that, when clicked on, drops down a list of open emails (i.e. a list of tabs). In the previous version of Thunderbird it would expand (vertically) to list all emails. However now it is a set vertical size and this is terrible and basically defeats the purpose. The purpose of that drop down was so that I did not have to scroll through all my open tabs to find an email. Now I have to do that again, as it is a set vertical size with arrows up and down to scroll through the list. How do I get the old functionality back, or solve my problem of somehow seeing a list of all open tabs? Thanks!