Bug 314685 EModelService's findElements(MUIElement, String, Class<T>, List<String>) method can return duplicates
I'm getting two editors in the returned list that's pointing at the same thing. The returned collection is a List and not a Set but this feels wrong.
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/workbench/ui/internal/ModelServiceImpl.java
MUIElement curParent = element.getParent();
		while (curParent != null && !(curParent instanceof MPerspective)
				&& !(curParent instanceof MWindow))
			curParent = curParent.getParent();
		if (curParent == null)
			return; 
		MWindow newWindow = BasicFactoryImpl.INSTANCE.createWindow();
		
		newWindow.setX(100);
		newWindow.setY(100);
		newWindow.setWidth(400);
		newWindow.setHeight(250);
		element.getParent().getChildren().remove(element);
		MWindowElement uiRoot = wrapElementForWindow(element);
		newWindow.getChildren().add(uiRoot);
		MElementContainer<MUIElement> windowParent = (MElementContainer<MUIElement>) curParent;
		windowParent.getChildren().add(newWindow);
	}
	/**
	 * @param element
	 * @return
	 */
	private MWindowElement wrapElementForWindow(MPartSashContainerElement element) {
		if (element instanceof MWindowElement)
			return (MWindowElement) element;
		return null;
	}
}