How?
On http://www.sonycreativesoftware.com/organizing_your_vegas_pro_workspace_pt1 it ells me to
"To dock the window back to the window docking area, drag it by the title bar into the area. When it gets close enough to the docking area, it snaps into place and resumes the appearance of a docked window. "
But it doesn't snap one bit when dragging windows.