It would be nice to be able to collapse the stacks in search mode. I use search mode for quick notebook swaps because it takes up minimal screen space when taking notes. Currently other stacks take up plenty of space when they aren't being used in this mode.
When I write notes in EN I enjoy having both the list of notes open as well as the smallest possible way to switch to a different notebook. I usually have a lecture opened to the left and EN on the right for a given screen. For this reason, I collapse the Left Panel, where you can collapse stacks and jump between notebooks.