It's somewhat of a bug, since it basically doesn't work at default window size on wxGTK (depending on the theme). My personal preference would be having collapsible panes for each section you see there on the side panel, so they could collapse and fit on screen. The problem is those aren't officially available on wxWidgets 2.8 (they are in 2.9). We could also use a scrolled window, like I recently added to the environment tab.