Hi Ben,

Yes, this was added as part of 10.2. Instead of including an <onClick> element, you'd include <originalText> instead. Its text content should be the name of the button on the default toolbar. Using the text attribute, you can choose to display it with either the same or different name.

https://www.labkey.org/issues/home/Developer/issues/details.view?issueId=10228

For example, to include the standard Export button but have it be called "Download This Content" instead, this should do the trick:

<buttonBarOptions position="both" includeStandardButtons="false">
    <item text="Download This Content">
        <originalText>Export</originalText>
    </item>
</buttonBarOptions>

I believe that the text attribute is required.

Thanks,
Josh