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
if (parentElement.getSelectedElement() == child) {
			
			Control tb = ctf.getTopRight();
			if (tb != null) {
				ctf.setTopRight(null);
				tb.dispose();
			}
			
			
			MUIElement defaultSel = getFirstVisibleElement(parentElement);
			parentElement.setSelectedElement(defaultSel);
		}
	}
	private MUIElement getFirstVisibleElement(
			MElementContainer<MUIElement> stack) {
		
		for (MUIElement mPart : stack.getChildren()) {
			if (mPart.isToBeRendered())
				return mPart;
		}
		return null;
	}
	@Override
	public void hookControllerLogic(final MUIElement me) {
		super.hookControllerLogic(me);
		if (!(me instanceof MElementContainer<?>))
			return;
		final MElementContainer<MUIElement> stack = (MElementContainer<MUIElement>) me;
		
		CTabFolder ctf = (CTabFolder) me.getWidget();