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
}
	}
	private void showElementRecursive(MUIElement element, List<MUIElement> becomingVisible) {
		if (!element.isToBeRendered())
			return;
		if (element instanceof MPlaceholder) {
			swap((MPlaceholder) element);
			element = ((MPlaceholder) element).getRef();
		}
		
		if (element instanceof MWindow && element.getWidget() != null) {
			element.setVisible(true);
		}
		becomingVisible.add(element);
		if (element instanceof MGenericTile<?>) {
			MGenericTile<?> container = (MGenericTile<?>) element;
			for (MUIElement childElement : container.getChildren()) {
				showElementRecursive(childElement, becomingVisible);
			}
		} else if (element instanceof MGenericStack<?>) {
			
			MGenericStack<?> container = (MGenericStack<?>) element;
			MUIElement curSel = container.getSelectedElement();
			showElementRecursive(curSel, becomingVisible);
		}
	}
	private void combine(MPartSashContainerElement toInsert, MPartSashContainerElement relTo,
			MPartSashContainer newSash, boolean newFirst, int ratio) {
		MElementContainer<MUIElement> curParent = relTo.getParent();
		int index = curParent.getChildren().indexOf(relTo);