private DockData GetDockData(ContentDocument pane)
{
if (pane.PreferredDockData != null) return pane.PreferredDockData;
DockingState dockState = pane.Control.DockingContainer.DockState == DockingState.Unknown ||
pane.Control.DockingContainer.DockState == DockingState.Hidden ?
DockingState.Document : pane.Control.DockingContainer.DockState;
return new DockData(dockState, Rectangle.Empty);
}