Widgets: 
- Don't deactivate "draggable" on the widget when the chooser is open. Makes it possible to still drag the "widget-in-question".
- Change the chooser's HTML id to a class to avoid collisions when cloning.
- Refresh the "sortable" positions when an open widget is dragged. Fixes problems moving the widget up or down in the same sidebar.
See #25821
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git-svn-id: http://core.svn.wordpress.org/trunk@26267 1a063a9b-81f0-0310-95a4-ce76da25c4cd