function display_doc( file_name ) {
	params = "width=400,height=400,menubar=yes,resizable=yes,scrollbars=yes";
	window.open("data/docs/" + file_name , "_blank" , params );
}
function display_tutorial( file_name ) {
	params = "width=400,height=400,menubar=yes,resizable=yes,scrollbars=yes";
	window.open("data/tutorials/" + file_name , "_blank" , params );
}
function display_image( file_name ) {
	params = "width=400,height=400,menubar=yes,resizable=yes,scrollbars=yes";
	window.open("data/images/" + file_name , "_blank" , params );
}