//usage add the three belowe event handlers to a textarea element.
//onkeydown="return insertTab(event,this);" 
//onkeyup="return insertTab(event,this);"  
//onkeypress="return insertTab(event,this);"

function insertTab(event,obj) {
			var tabKeyCode = 9;
			if (event.which) // mozilla
				var keycode = event.which;
			else // ie
				var keycode = event.keyCode;
				if (keycode == tabKeyCode) {
					if (event.type == "keydown") {
						if (obj.setSelectionRange) {
							// mozilla
							var s = obj.selectionStart;
							var e = obj.selectionEnd;
							obj.value = obj.value.substring(0, s) + 
							"\t" + obj.value.substr(e);
							obj.setSelectionRange(s + 1, s + 1);
							obj.focus();
						} else if (obj.createTextRange) {
							// ie
							document.selection.createRange().text="\t"
							obj.onblur = function() { this.focus(); this.onblur = null; };
							} else {
								// unsupported browsers
						}
					}
					if (event.returnValue) // ie ?
						event.returnValue = false;
					if (event.preventDefault) // dom
						event.preventDefault();
						return false; // should work in all browsers
				}
			return true;
		}