clickposx = 0;
clickposy = 0;

scrollstartleft = 0;
scrollstarttop  = 0;

ismousedown = false;

maxleft = 0;
maxtop  = 0;

function setClickPos(event, targetDiv) {

	clickposx = event.screenX;
	clickposy = event.screenY;

	scrollstartleft = parseInt(targetDiv.style.left);
	scrollstarttop = parseInt(targetDiv.style.top);
	
	var framingDiv = document.getElementById("main-window");

	maxleft = parseInt(targetDiv.style.width) - parseInt(framingDiv.style.width);
	maxtop = parseInt(targetDiv.style.height) - parseInt(framingDiv.style.height);

	ismousedown = true;
}

function mouseup(event, target) {
	ismousedown = false;
}

function moveTarget(event, target) {
	if (ismousedown == true) {
		var newposx = event.screenX;
		var newposy = event.screenY;
		
		var difx = newposx - clickposx;
		var dify = newposy - clickposy;

		var newleft = scrollstartleft + difx;
		if (newleft > 0) { newleft = 0; }
		if (newleft < (0 - maxleft)) { newleft = (0 - maxleft); }

		var newtop = scrollstarttop + dify;
		if (newtop > 0) { newtop = 0; }
		if (newtop < (0 - maxtop)) { newtop = (0 - maxtop); }

		moveToPosition(target, newleft, newtop);
	}
}

function moveToPosition(target, x, y) {
	target.style.left = "" + x + "px";
	target.style.top = "" + y + "px";
}

window.onload = function() {
  document.onselectstart = function() {return false;} // ie
  document.onmousedown	 = function() {return false;} // mozilla
}