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/internal/workbench/ModelServiceImpl.java
newSash.setHorizontal(false);
				newSash.setContainerData(relTo.getContainerData());
				combine(toInsert, relTo, newSash, newFirst, ratio);
			} else if (!curTile.isHorizontal() && (where == LEFT_OF || where == RIGHT_OF)) {
				MPartSashContainer newSash = BasicFactoryImpl.eINSTANCE.createPartSashContainer();
				newSash.setHorizontal(true);
				newSash.setContainerData(relTo.getContainerData());
				combine(toInsert, relTo, newSash, newFirst, ratio);
			} else {
				
				int relToIndex = relTo.getParent().getChildren().indexOf(relTo);
				if (newFirst) {
					curTile.getChildren().add(relToIndex, toInsert);
				} else {
					curTile.getChildren().add(relToIndex + 1, toInsert);
				}
				
				int relToWeight = 100;
				if (relTo.getContainerData() != null) {
					try {
						relToWeight = Integer.parseInt(relTo.getContainerData());
					} catch (NumberFormatException e) {
					}
				}
				int toInsertWeight = (int) ((ratio / 100.0) * relToWeight + 0.5);
				relToWeight = relToWeight - toInsertWeight;
				relTo.setContainerData(Integer.toString(relToWeight));
				toInsert.setContainerData(Integer.toString(toInsertWeight));
			}
		}