With the current DOpus drive button configuration, clicking on a drive will display that drive in the right-hand file display. The configuration can be changed to display the drive in the left-hand file display. Those who want the option to display in wither side must either (2) create two drive configurations, or (b) manually create a button for each drive that displays in the drive in a particular file display through a right-click/left click configured 3-button or via a left-click and key combo (ie hold down ctrl while left-clicking on drive).
Request DOpus enhance drive button to display selected drive in right or left file display based on right or left mouse click by default.