BlockUI unblocks lower level item when a higher level container is unblocked, is it supposed to do that?

BlockUI unblocks lower level item when a higher level container is unblocked, is it supposed to do that?

I have a set of tabs:

$("#documentssubmenu").tabs({
ajaxOptions: {
error: function(xhr, status, index, anchor) {
$(anchor.hash).html("Couldn't load this tab. We'll try to fix this as soon as possible. If this wouldn't be a demo.");
}
},
show: function(event,ui) {
console.info("documentssubmenu::show");
blockCurrentTab(ui.panel.id);
},
load: function(event,ui) {
console.info("documentssubmenu::load");
$('#' + ui.panel.id).unblock();
},
select: function(event,ui) {
console.info("documentssubmenu::select");
blockCurrentTab(ui.panel.id);
}
//,cache: true <-- turn me back on after testing!
});

And then on the page within the tab I have:

$("#listuserstablediv").block();

When the page loads I have it block  the element on page, but when the tabs load method fires it takes out the block not only on the tab, but also on #listuserstablediv. Is it supposed to do that? Do you consider this a bug or is there a way to work this in as a feature? I figure if I wanted to unblock everything I would have done a $.unblockUI or specified both elements. Thanks!

Shaun