How to add a context-sensitive help question-mark icon and hook it up.
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Now, in the ui.xml of your widget, import the help package, pull in the HelpMessages external resource, and use the HelpButton (using the key in the properties file for the content, and url to the help page):
xmlns:h="urn:import:org.sagebionetworks.web.client.help"
<ui:with field='help' type='org.sagebionetworks.web.client.help.HelpMessages' />
<h:HelpButton href="https://docs.synapse.org/discussionForum" placement="RIGHT">
<bh:Text><ui:text from='{help.discussionForum}'/></bh:Text>
</h:HelpButton>
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