var defaultButtonName;
function HandleDefaultButton()
{
	if (event.keyCode == 13)
	{
		if (event.srcElement.tagName == 'TEXTAREA')
		{
			// if user press "enter" in textarea box , not handle it 
			var txtArea = document.getElementById(event.srcElement.id);
			if(txtArea.readOnly == true)
			{
				event.returnValue = false;
			}
			
		}
		else
		{
			defaultButtonName = defaultButtonName + '';
			if(defaultButtonName == 'undefined')
			{
				defaultButtonName = 'btnOk';
			}
			var button = document.getElementById(defaultButtonName);
			if (button !=null && (button.type == 'submit' || button.type == 'image'))
			{
				// if user press "enter", fire the click event of the default button
				event.returnValue = false;
				event.cancel = true;
				button.click();
			}
			else
			{
				// there isn't default button, ignore it
				event.returnValue = false;
			}
		}
		
	}
}