abstract class DomImpl {

 /**
  * Create instance of [DomImpl] depends on broswer.
  */
 factory DomImpl.browserDependent() {
   return new DomImplStandard();
 }

 DomImpl();

 static bool eventSystemIsInitialized = false;

 /**
  * The attribute that is set when an image fires a native load or error event
  * before it is attached.
  */
 static final String UNHANDLED_EVENT_ATTR = "dwtLastUnhandledEvent";

 //*************************
 // Parent - child relations
 //*************************

 bool isOrHasChild(dart_html.Node parent, dart_html.Node child);

 void insertChild(dart_html.Element parent, dart_html.Element child, int index);

 dart_html.Element getChild(dart_html.Element elem, int index);

 int getChildCount(dart_html.Element elem);

 //********************
 // Position of Element
 //********************

 int getAbsoluteLeft(dart_html.Element elem);

 int getAbsoluteTop(dart_html.Element elem);

 //*********
 // Capturte
 //*********

 void releaseCapture(dart_html.Element elem);

 void setCapture(dart_html.Element elem);

 //******
 // Style
 //******
 
 String getStyleProperty(dart_html.Element elem, String name);
 
 void setStyleProperty(dart_html.Element elem, String name, String value);
 
 String get cssFloatPropertyName {
   return "cssFloat";
 }
 
 //*******
 // Events
 //*******

 void maybeInitializeEventSystem() {
   if (!eventSystemIsInitialized) {
     initEventSystem();
     eventSystemIsInitialized = true;
   }
 }

 /**
  * Initializes the event dispatch system.
  */
 void initEventSystem();

 void setEventListener(dart_html.Element elem, EventListener listener);

 void sinkBitlessEvent(dart_html.Element elem, String eventTypeName);

 void sinkEvents(dart_html.Element elem, int eventBits);

 int getEventsSunk(dart_html.Element elem) {
   return _getEventBits(elem);
 }

 int _getEventBits(dart_html.Element elem) {
   assert(elem != null);
   String eventBits = elem.dataset["eventBits"];
   if (eventBits != null) {
     try {
       return int.parse(eventBits);
     } on Exception catch(e) {}
   }
   return 0;
 }

 void _setEventBits(dart_html.Element elem, int bits) {
   assert(elem != null);
   assert(bits != null);
   elem.dataset["eventBits"] = bits.toRadixString(16);
 }

 dart_html.Element eventGetToElement(dart_html.Event evt);

 int getEventTypeInt(dart_html.Event evt) {
   return eventGetTypeInt(evt.type);
 }

 int eventGetTypeInt(String eventType) {
   switch (eventType) {
     case "blur": return 0x01000;
     case "change": return 0x00400;
     case "click": return 0x00001;
     case "dblclick": return 0x00002;
     case "focus": return 0x00800;
     case "keydown": return 0x00080;
     case "keypress": return 0x00100;
     case "keyup": return 0x00200;
     case "load": return 0x08000;
     case "losecapture": return 0x02000;
     case "mousedown": return 0x00004;
     case "mousemove": return 0x00040;
     case "mouseout": return 0x00020;
     case "mouseover": return 0x00010;
     case "mouseup": return 0x00008;
     case "scroll": return 0x04000;
     case "error": return 0x10000;
     case "mousewheel": return 0x20000;
     case "DOMMouseScroll": return 0x20000;
     case "contextmenu": return 0x40000;
     case "paste": return 0x80000;
     case "touchstart": return 0x100000;
     case "touchmove": return 0x200000;
     case "touchend": return 0x400000;
     case "touchcancel": return 0x800000;
//      case "gesturestart": return 0x1000000;
//      case "gesturechange": return 0x2000000;
//      case "gestureend": return 0x4000000;
     default: return -1;
   }
 }

 dart_html.Event createHtmlEvent(String type, bool canBubble, bool cancelable);

 EventListener getEventListener(dart_html.Element elem);
}