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
public static final int ABOVE = 0;
	public static final int BELOW = 1;
	public static final int LEFT_OF = 2;
	public static final int RIGHT_OF = 3;
	/**
	 * Return a list of any elements that match the given search criteria. The search is recursive
	 * and includes the specified search root. Any of the search parameters may be specified as
	 * <code>null</code> in which case that field will always 'match'.
	 * <p>
	 * NOTE: This is a generically typed method with the List's generic type expected to be the
	 * value of the 'clazz' parameter. If the 'clazz' parameter is null then the returned list is