Check sidebar content to make sure it resizes to fit sidebar width

[bhousel]

As reported on Discord, sometimes the sidebar content can end up wider than it should be, causing the buttons on the right to be cut off. In this example below, the user reported that there were some relations with a very long name.

https://github.com/user-attachments/assets/3564f31b-0723-4a1b-91fa-9c276df25255

regressed in #1497