Bug 304211 StackRenderer does not set eagerly created controls to the item
Right-clicking on a Java element and then using 'Open Declaration' opens an editor on the specified file but its content is not shown. Switching tabs or selecting items in the 'Outline' view does _not_ help. Seems to be calling IWorkbenchPage's APIs properly. No idea yet as to what's going on over here.
bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/workbench/ui/renderers/swt/StackRenderer.java
cti.setData(OWNING_ME, part);
		cti.setText(getLabel(itemPart, itemPart.getLabel()));
		cti.setImage(getImage(itemPart));
		cti.setToolTipText(itemPart.getTooltip());
		if (part.getWidget() != null)
			cti.setControl((Control) part.getWidget());
	}
	private int calcIndexFor(MElementContainer<MUIElement> stack,
			final MUIElement part) {
		int index = 0;
		
		for (MUIElement mPart : stack.getChildren()) {
			if (mPart == part)
				return index;
			if (mPart.isToBeRendered())
				index++;
		}
		return index;
	}
	@Override
	public void childRendered(
			final MElementContainer<MUIElement> parentElement,
			MUIElement element) {
		super.childRendered(parentElement, element);
		if (!(((MUIElement) parentElement) instanceof MPartStack)
				|| !(element instanceof MPart))
			return;
		createTab(parentElement, element);
	}
	private CTabItem findItemForPart(MUIElement part) {