This JavaScript function will resize the inside of a browser window to the dimensions provided.

function innerResizeWindow(innerWidth, innerHeight) {
        if (self.innerWidth) {
                myInnerWidth = self.innerWidth;
                myInnerHeight = self.innerHeight;
        }
        else if (document.documentElement && document.documentElement.clientWidth) {
                myInnerWidth = document.documentElement.clientWidth;
                myInnerHeight = document.documentElement.clientHeight;
        }
        else if (document.body) {
                myInnerWidth = document.body.clientWidth;
                myInnerHeight = document.body.clientHeight;
        }
        else {
                return;
        }
        adjustWidth = innerWidth - myInnerWidth;
        adjustHeight = innerHeight - myInnerHeight;
        window.resizeBy(adjustWidth, adjustHeight);
}
window.onload = innerResizeWindow(800,600);