Bug 320142 Editors no longer activate when clicking on their tabs
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/ModelServiceImpl.java
persp.setToBeRendered(false);
		MUIElement psElement = persp.getParent();
		MPerspectiveStack ps = (MPerspectiveStack) psElement;
		ps.getChildren().remove(persp);
		if (ps.getSelectedElement() == persp) {
			for (MPerspective p : ps.getChildren()) {
				if (p != persp && p.isToBeRendered()) {
					ps.setSelectedElement(p);
					return;
				}
			}
			ps.setSelectedElement(null);
		}
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.e4.ui.workbench.modeling.EModelService#getActivePerspective(org.eclipse.e4.ui
	 * .model.application.ui.basic.MWindow)
	 */
	public MPerspective getActivePerspective(MWindow window) {
		List<MPerspectiveStack> pStacks = findElements(window, null, MPerspectiveStack.class, null);
		if (pStacks.size() == 1)
			return pStacks.get(0).getSelectedElement();
		return null;
	}
}