Is it possible to change the default button in the warning dialog when changing class for a customer?

We would like the warning dialog when changing the customer class to default to No rather than Yes.  I have looked at the code and found where it is defined:

protected virtual void Customer_CustomerClassID_FieldVerifying(PXCache cache, PXFieldVerifyingEventArgs e)
		{
			Customer row = (Customer)e.Row;
			CustomerClass cc = (CustomerClass)PXSelectorAttribute.Select<Customer.customerClassID>(cache, row, e.NewValue);
			this.doCopyClassSettings = false;
			if (cc != null)
			{
				this.doCopyClassSettings = true;
				if (cache.GetStatus(row) != PXEntryStatus.Inserted)
				{
					if (BAccount.Ask(Messages.Warning, Messages.CustomerClassChangeWarning, MessageButtons.YesNo) == WebDialogResult.No)
					{
						this.doCopyClassSettings = false;
					}
				}
			}
		}

Is there a way to specify which button (Yes/No) should be the default?

Thanks,

Phil