private DockableState removePreviousFloatingStates(
			TabbedDockableContainer tdc) {
		DockableState first = removePreviousFloatingState(tdc.getDockableAt(0));
		for (int i = 1; i < tdc.getTabCount(); i++) {
			Dockable d = tdc.getDockableAt(i);
			removePreviousFloatingState(d);
		}
		return first;
	}