Not sure if this is a bug or by design, but I noticed today that when attempting to get the height of a dialog window that hasn't been created yet, it returns an Object instead of "undefined" as it did in 1.7.2.

1. $("#dialog").dialog( "option","height" );

returns  [object Object] if #dialog has not already been turned into a dialog yet.

This breaks code like:

2. if ( !$("#dialog").dialog( "option", "height" ) ) {
3.     $("#dialog").dialog();
4. }

Maybe it has something to do with whether #dialog already exists (as a div) on the page

http://jsbin.com/osulu