Scroll properties editor with horizontal alignment

I set up the Blender interface to be split vertically so there are three sections that span the whole horizontal width of the screen. The top section takes up 80% of the height and is the 3D view. In the section below it I set the editor type to properties. At the bottom is a section set to the timeline which is very thin. I set the align type of the properties view to horizontal.

I cannot scroll the properties view vertically past a certain point. I can press or roll the middle mouse wheel to scroll the properties window up to a certain point but then it stops scrolling, even if there are more dialogs to display. How can I get the properties view to scroll enough so that all dialogs are visible.