/**
 * _ti - id elementu, ktery chci skrolovat
 * _bb - tlacitko zpet
 * _bb - tlacitko dopredu
 */
function SimpleVerticalScroller (_ti, _bb, _bf) {
   var ref = this;
   this.ti = SJEL.$(_ti);
   SJEL.SStyle(this.ti, {
      overflow: "hidden"
   });
   this.bb = SJEL.$(_bb);
   this.bf = SJEL.$(_bf);
   this.tii = SJEL.CE("div");
   this.tii.innerHTML = this.ti.innerHTML;
   this.ti.innerHTML = "";
   this.ti.appendChild(this.tii);
   this.max = this.ti.offsetHeight - this.tii.offsetHeight;
   this.step = 4;
   this.mt = 0;  // margin-top
   this.bfe = this.bbe = false;

   if (this.max >= 0)  // vyska this.ti je vetsi jak vnitrek this.ti
      return;

   SJEL.AddClass(this.bb, "bw_vert_but");
   SJEL.AddClass(this.bf, "fw_vert_but");
	
   this.bfe = true;
   SJEL.AddClass(this.bf, "fw_vert_but_on");

   this.OnButBTimer = function () {
      ref.mt += ref.step;
      if (ref.mt > 0) {
	 ref.mt = 0;
	 ref.tab.Stop();
	 SJEL.RemoveClass(ref.bb, "bw_vert_but_on");
	 ref.bbe = false;
      }
      /*if (SJEL.ie && !ref.mt)
			ref.mt = 0;*/
      SJEL.SStyle(ref.tii, {
	 marginTop: ref.mt + "px"
	 });
      if (!ref.bfe) {
	 SJEL.AddClass(ref.bf, "fw_vert_but_on");
	 ref.bfe = true;
      }
   }

   this.OnButFTimer = function () {
      ref.mt -= ref.step;
      if (ref.mt < ref.max) {
	 ref.mt = ref.max;
	 ref.taf.Stop();
	 SJEL.RemoveClass(ref.bf, "fw_vert_but_on");
	 ref.bfe = false;
      }
      /*if (SJEL.ie && !ref.mt)
			ref.mt = 0;*/
      SJEL.SStyle(ref.tii, {
	 marginTop: ref.mt + "px"
	 });
      if (!ref.bbe) {
	 SJEL.AddClass(ref.bb, "bw_vert_but_on");
	 ref.bbe = true;
      }
   }

   this.tab = new SJEL.Timer(this.OnButBTimer, 500, 20);
   this.tab.SetFps(30);
   this.taf = new SJEL.Timer(this.OnButFTimer, 500, 20);
   this.taf.SetFps(30);
	
   this.bb.onmouseover = function () {
      ref.tab.Start(true);
   }
   this.bb.onmouseout = function () {
      ref.tab.Stop();
   }

   this.bf.onmouseover = function () {
      ref.taf.Start(true);
   }
   this.bf.onmouseout = function () {
      ref.taf.Stop();
   }
}