Added the FloatingWindowShowInTaskBarMode.Always option, which lets floating tool windows appear in the task bar.
Updated the Prism sample's DockSiteRegionBehavior to properly remove a view from the region when a related docking window is unregistered from its dock site.
Improved system dragging over tabs to properly indicate no drop is supported, while still allowing tabs to be selected on hover.
Improved focus logic.
Improved logic for determining when a tab is about to drag in scenarios where the tab control is moved on selection due to external controls being added to the layout.