Jquery.ui.diaglog.js drag containment Bug

Here it is:

I just found that there might have a Bug in the Jquery.ui.diaglog.js

as we know there is a paramerter called "containment" between dragable & resizable.and it's default value is "document".it controls the draging always keeping in the document area.

but when the target page is not an entire page. when it's an opened small page. and also included a dragable dialog..then it doesn't work I think..at least the range we can control is truning too small.

so here is my solution:

add a paramerter called "options.containment"(for example)..the default value is "document".and the relevant containments of draggable & resizable also can be changed to "options.containment"...then we can control it easily.