var tString = '';
var lsf = 0;	// last successful index
		         
		         
		function evalKey() {
			// Global Variables
			var i = 0; 
			var success = false;
			var elem = event.srcElement;
			var tLowElemText = '';
			// Get the unicode char of the keypress
			var eCode = event.keyCode;
			// Check if it's a vaid ASCII Character
			if (eCode == 27){
				tString = ''; 
				elem.selectedIndex = 0;
				}
			else if ( (eCode > 31) && (eCode < 122))
				{
				// Convert the Code to the corresponding character and add to searchstring
				tString += String.fromCharCode(eCode);
				// ... and perform the search starting from the top element in the listbox
				while (success == false) 	
					{
						i = 0;
						// Convert everything to lowercase; allows an easy comparison
						var tLowString = tString.toLowerCase();
						// Compose the regexp searchstring ...
						var rExpr = eval("/^" +  tLowString + "/");
						while ((i < elem.length)&& (success == false) )	
							{
								tLowElemText = elem.options[i].text.toLowerCase();
								// success: Position the listbox on the (first) found element
								if (tLowElemText.search(rExpr) != -1)
									{
										elem.selectedIndex = i;
										success = true;
									}
								else {
										i++; }
									} // while i < elem.length
								// if nothing is found in the entire list, the last character of the
								//searchstring is removed to allow typing the correct 'next' character
								if (success == false) {
									tString = tString.substr(0, tString.length-1);
							}
					} // while success = false
				}
		         
				window.event.returnValue = false;
				window.event.cancelBubble = true;
		}