// comments cut--they are in the home page grammar.htm, gr-chase.all
var oChaser = {
topMargin: 3,
callRate: 10,
slideTime: 1200,
maxDiff: document.all ? document.body.clientHeight : window.innerHeight,
isIE: document.all ? true : false,
chaserDiv: document[document.all ? "all" : "layers"]["chaser"]
}
window.setInterval("oChaser.main( )", oChaser.callRate)
oChaser.main = function( )
{
	this.currentY = this.isIE ? this.chaserDiv.style.pixelTop : this.chaserDiv.top
	this.scrollTop = this.isIE ? document.body.scrollTop : window.pageYOffset
	var newTargetY = this.scrollTop + this.topMargin
	
	if ( this.currentY != newTargetY ) {
		if ( newTargetY != this.targetY ) {
			this.targetY = newTargetY
			this.slideInit( )
		}
		this.slide( )
	}
}
oChaser.slideInit = function( )
{
	var now	= new Date( )
		this.A = this.targetY - this.currentY
		this.B = Math.PI / ( 2 * this.slideTime )
		this.C = now.getTime( )
	if (Math.abs(this.A) > this.maxDiff) {
		this.D = this.A > 0 ? this.targetY - this.maxDiff : this.targetY + this.maxDiff
		this.A = this.A > 0 ? this.maxDiff : -this.maxDiff
	} else {
		this.D = this.currentY
	}
}
oChaser.slide = function( )
{
	var now	= new Date( )
	var newY = this.A * Math.sin( this.B * ( now.getTime( ) - this.C ) ) + this.D
	newY = Math.round( newY )

	if (( this.A > 0 && newY > this.currentY ) ||
		( this.A < 0 && newY < this.currentY )) {
			if ( this.isIE )this.chaserDiv.style.pixelTop = newY
			else this.chaserDiv.top = newY
	}
}