[code]
<html>

<head>
   <title>Time counter</title>
   <script type="text/javascript">
      var mouseDown = false;
      var countType;
      var counter = 0;
      var nextTime;
      var minutes;
      var hours;

      function hour ()
      {
         if (isNaN(hours.value))
         {
            hours.value = "00";
         }

         if (countType)
         {
            if (hours.value == 23)
            {
               hours.value = "00";
            }
            else
            {
               hours.value ++;
            }
         }
         else
         {
            if (hours.value == 00)
            {
               hours.value = "23";
            }
            else
            {
               hours.value --;
            }
         }

         if (hours.value < 10 && hours.value > 0)
         {
            hours.value = "0" + hours.value;
         }
      }

      function count ()
      {
         if (mouseDown)
         {
            if (isNaN(minutes.value))
            {
               minutes.value = "00";
            }

            counter++;

            if (countType)
            {
               if (minutes.value == 59)
               {
                  minutes.value = "00";
                  hour();
               }
               else
               {
                  minutes.value ++;
               }
            }
            else
            {
              if (minutes.value == 00)
               {
                  minutes.value = "59";
                  hour();
               }
               else
               {
                  minutes.value --;
               }
            }

            if (minutes.value < 10 && minutes.value > 0)
            {
               minutes.value = "0" + minutes.value;
            }

            nextTime = 200 / counter;

            if (nextTime < 10)
            {
               nextTime = 5;
            }

            setTimeout('count();', nextTime);
         }
      }

      function startCount (type, idMinutes, idHours)
      {
         mouseDown = true;
         countType = type;
         minutes = document.getElementById(''+idMinutes+'');
         hours = document.getElementById(''+idHours+'');
         counter = 0;
         count();
      }

      function stopCount ()
      {
         mouseDown = false;
      }
   </script>

   <style type="text/css">
      #scheidingsteken
      {
         float: left;
         font-weight: bold;
      }

      #up
      {
         position: absolute;
         right: 0px;
         top: 0px;
      }

      #down
      {
         position: absolute;
         right: 0px;
         bottom: 0px;
      }

      #uren
      {
         border: 1px solid #ccc;
         float: left;
         position: relative;
         width: 20px;
      }

      #uren input
      {
         border: 0;
         font: 11px verdana;
         width: 20px;
      }

      #minuten
      {
         border: 1px solid #ccc;
         float: left;
         position: relative;
         width: 35px;
      }

      #minuten input
      {
         border: 0;
         font: 11px verdana;
         width: 35px;
      }
   </style>
</head>

<body>
   <div id="uren">
      <input disabled="disabled" id="uren_input" maxlength="2" type="text" value="<?php echo date('H'); ?>" />
   </div>
   <div id="scheidingsteken">
      :
   </div>
   <div id="minuten">
      <input disabled="disabled" id="minuten_input" type="text" maxlength="2" value="<?php echo date('i'); ?>" />
      <img id="up" src="up.gif" onmousedown="startCount(true, 'minuten_input', 'uren_input');" onmouseup="stopCount();" onmouseout="stopCount();" />
      <img id="down" src="down.gif" onmousedown="startCount(false, 'minuten_input', 'uren_input');" onmouseup="stopCount();" onmouseout="stopCount();" />
   </div>
</body>

</html>
[/code]