Dynamic sidebar width
When making a window with a sidebar narrower the sidebar and content pane should ideally both shrink.
Currently sidebars are fixed width and only the content pane shrinks, which leads to the app looking weird at sizes just above the folding point, and also means that we need to fold sooner than otherwise necessary.
A prominent example of this is Settings, where this is the smallest size you can scale to before the leaflet folds:
Which leads to this awkward folded state:
Edited by Tobias Bernard