You can achieve that using the open_node event - listen for it, and
when it occurs close all other nodes on the same level.
$("#container").bind("open_node.jstree", function (e, data) {
data.rslt.obj.siblings().filter(".jstree-open").each(function () {
data.inst.close_node(this);
});
});
You can also disable the animations if you will.
Kindest regards,
Ivan