function mxKeyHandler(a,b){null!=a&&(this.graph=a,this.target=b||document.documentElement,this.normalKeys=[],this.shiftKeys=[],this.controlKeys=[],this.controlShiftKeys=[],this.keydownHandler=mxUtils.bind(this,function(c){this.keyDown(c)}),mxEvent.addListener(this.target,"keydown",this.keydownHandler),mxClient.IS_IE&&mxEvent.addListener(window,"unload",mxUtils.bind(this,function(){this.destroy()})))}mxKeyHandler.prototype.graph=null;mxKeyHandler.prototype.target=null;