All the jQuery UI plugins allow you to fetch cached references to the widget's proxy elements by grabbing the instance from the jQuery data cache.

var tabs = $("#mytabs").data("tabs"); tabs.lis.append("<button>Add A Button To All your Tabs</button>");

You can use this to avoid doing crazy DOM traversals to work with and customise widget components.

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That said, we are aware that the perception you share here is not uncommon and that we need to work to document the shared API of our widgets, and that is something we are planning to address in the near term.