Bug 327033 Workbench doesn't relayout after a stack disappears
If you close all the views of a stack, you just get an empty rectangle of space now. Resizing your window will adjust the layout properly. Note that reopening the views don't help, you still have to resize something to force a layout.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/SashRenderer.java
&& !(parentElement instanceof MArea)) {
			prevParent = parentElement;
			parentElement = parentElement.getParent();
		}
		if (parentElement.getRenderer() instanceof AbstractPartRenderer) {
			AbstractPartRenderer renderer = (AbstractPartRenderer) parentElement
					.getRenderer();
			return renderer.getUIContainer(prevParent);
		}
		return null;
	}
	/**
	 * @param element
	 * @return
	 */
	private static int getWeight(MUIElement element) {
		String info = element.getContainerData();
		if (info == null || info.length() == 0) {
			element.setContainerData(Integer.toString(100));
			info = element.getContainerData();
		}
		try {
			int value = Integer.parseInt(info);
			return value;
		} catch (NumberFormatException e) {
			return UNDEFINED_WEIGHT;
		}
	}
}