In WB 7.4, not sure about later versions:
Open WB Config (where you change skins)
Click on "Settings" tab at the top of main window
New window comes up, click on "Settings" tab at top of that window (probably already comes up there)
Bottom 2 options on that window are "Action to take when double clicking on a titlebar" and "Action to take when right clicking on a titlebar". Either one can be set to "Rollup/Down Window" from the dropdown menus on their right.
Easier than finding skins with the button and more consistent.