call this function:

function channelUserInput() {
	$("body").append("<div id='screen'></div>");

	$("#screen").css({
		'display' : 'block',
		opacity : 0.7,
		'width' : $(document).width(),
		'height' : $(document).height()
	});

//This is the problematic line!
	$("body").css({
		'overflow' : 'hidden'
	});
}

from otherFunction (see below) and if otherFunction receives as a parameter an object (in this case a Java object from an applet code) it will lose context and with it all knowledge of that parameter but not of other primitive type parameters :p

so:

function otherFunction(myObject, aString) {
    myObject.something(); // works
    channelUserInput(); // works
    myObject.something(); // FAILS 
    //javascript just lost reference to myObject but not to aString
}