Working with Combobox

I got ComboBox, populated by some values from provider (ISelectItemProvider) and I want to execute method that is executed everytime I select another value, something like this:

	public void checkSelectedValue(){
		if(getSelectOneCombobox().getValue().toString().equals("some value")) {
			renderCommunicate = true;

As you can see, I’v tried with control accessor, another try was with content provider attached to this combobox, nothing seems to work tho. What’s more, how do I actually bind this method to execute everytime I select another value?