//when continue clicked, checks if values are null
//If not, call main pages continue event handler
private void continue_Click(object sender, RoutedEventArgs e)
{
if (cbGender.SelectedItem != null && cbAge.SelectedItem != null)
{
mainPage.continue_Click(sender, e);
}
else
{
validationDialog("You have not entered valid details, please fill out the form before continuing");
}
}