Scroll screen with pageup/pagedown keys and cursor keys
Because the mouse scroll wheel operates the volume sliders, there is a need for scrolling the page (e.g. Playback tab page) with the keyboard. It is really cumbersome to have to hunt for the scrollbar.
Should be easy to fix using some standard GTK feature, for those who are already well versed in GTK.
Bonus feature along the same lines of usability improvement: Add filter functionality for audio stream names/types. I have many streams and often cannot find the right one quickly.