Bug 323832 [UI] SashContainers are not being removed when unneeded
Start with a fresh workspace Drag the Problems view to the right of its current stack Drag it back... The problem is that the original drag created an MPartSashContainer to host the new stack but the drag back doesn't remove it (i.e. after dragging the Problems view back to its original stack there's now an MPSC with *only* the one stack in it).
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/workbench/modeling/EModelService.java
* @param where
	 *            An SWT constant indicating where the inserted element should be placed
	 * @param ratio
	 *            The percentage of the area to be occupied by the inserted element
	 */
	public void insert(MPartSashContainerElement toInsert, MPartSashContainerElement relTo,
			int where, int ratio);
	/**
	 * Created a separate (detached) window containing the given element.
	 * 
	 * @param mPartSashContainerElement
	 *            The element to detach
	 * @param x
	 *            The X position of the new window
	 * @param y
	 *            The Y position of the new window
	 * @param width
	 *            The Width of the new window
	 * @param height
	 *            The Height of the new window
	 */
	public void detach(MPartSashContainerElement mPartSashContainerElement, int x, int y,
			int width, int height);
	public MWindow getTopLevelWindowFor(MUIElement element);
	public MPerspective getPerspectiveFor(MUIElement element);
	public MTrimBar getTrim(MTrimmedWindow window, SideValue sv);
	public MPerspective getActivePerspective(MWindow window);
	public void removePerspectiveModel(MPerspective persp, MWindow window);
}