Bug 126839 [DataBinding] IObservable refactoring
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/swt/CComboUpdatableCollection.java
}
			});
		} else {
			throw new IllegalArgumentException();
		}
	}
	public int computeSize() {
		return ccombo.getItemCount();
	}
	public int addElement(Object value, int index) {
		updating=true;		
		try {
			if (index<0 || index>computeSize()) {
				index=computeSize();
			}
			String[] newItems = new String[computeSize()+1];			
			System.arraycopy(ccombo.getItems(), 0, newItems,0, index);
			newItems[index]=(String)value;
			System.arraycopy(ccombo.getItems(), index, newItems,index+1, computeSize()-index);
			ccombo.setItems(newItems);
			fireChangeEvent(ChangeEvent.ADD, null, value, index);
		}
		finally{
			updating=false;
		}
		return index;
	}
	public void removeElement(int index) {
		updating=true;		
		try {