public delegate void AddCustomFunctionsEventHandler(Dictionary<string, AdvancedKeywordInfo> functions);

public event AddCustomFunctionsEventHandler CustomizeFunctions;

CustomControl.CustomizeFunctions += CustomControl_CustomizeFunctions;

void CustomControl_CustomizeFunctions(Dictionary<string, AdvancedKeywordInfo> functions)
{
            
}

private void CustomControl_CustomizeFunctions()
{

}