Bug 327585 Commands, Handlers, and keybindings should use leaf lookup
bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/workbench/modeling/ExpressionContext.java
private boolean allowActivation = false;
	private IEclipseContext eclipseContext;
	public ExpressionContext(IEclipseContext eclipseContext) {
		this.eclipseContext = eclipseContext;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.expressions.IEvaluationContext#getParent()
	 */
	public IEvaluationContext getParent() {
		return null;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.expressions.IEvaluationContext#getRoot()
	 */
	public IEvaluationContext getRoot() {
		return this;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.core.expressions.IEvaluationContext#setAllowPluginActivation(boolean)