Only way to fix the scroll issue is to allow overflow on body. To keep the overflow at its minimum, I've set the source pane's height to inner height - 37 (37px is the fixed height of the search bar).
Then added 1 px to trigger the overflow. This allows scrolling the source pane in case the xml is too long.
68 Weird scroll problem in chrome, weirder fix.
Only way to fix the scroll issue is to allow overflow on body. To keep the overflow at its minimum, I've set the source pane's height to inner height - 37 (37px is the fixed height of the search bar). Then added 1 px to trigger the overflow. This allows scrolling the source pane in case the xml is too long.