Draggable: Change $.ui.contains() to $.contains(). Fixes #9051 - Draggable: Reference to undefined $.ui.contains().
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Dialog: Don't use ._on() for modal event handlers. Fixes #9048 - Dialog: broken focusin event handler when beforeclose event of a modal opens another modal.
Dailog: Cover iframes during drag and resize. Fixes #7650 - Dialog cannot be dragged properly with IFRAME.