function BB_Code (textbox_name, preText, postText )
{
var textbox = document.getElementById(textbox_name);
var textRange;

postText = postText || "";

textbox.focus();

if ( textbox.selectionStart !== undefined )
	{
		var startPos = textbox.selectionStart;
		var endPos = textbox.selectionEnd;
		var selectedText = textbox.value.substring (startPos, endPos);
		
		textbox.value = textbox.value.substring (0, startPos) +
						preText + selectedText + postText +
						textbox.value.substring (endPos, textbox.value.length);
						
		textbox.selectionStart = startPos + preText.length;
		textbox.selectionEnd = textbox.selectionStart;
		}

else if (document.selection !== undefined )
	{
		textRange = document.selection.createRange();
		var originalText = textRange.text;
		
		textRange.text = preText + textRange.text + postText;
		textRange.moveStart ("character", -(postText.length + originalText.length));
		textRange.moveEnd ("character", -(postText.length + originalText.length));
		textRange.select();
	}
	else
	{
		textbox.value += text;
	}
	
	textbox.focus();
}