Gadget export
To export the ProveIt-classic gadget, click on "Download" button, save the downloaded file, go to Special:Import on destination wiki and upload it. Then add the following to MediaWiki:Gadgets-definition page:
* ProveIt-classic[ResourceLoader|type=general|dependencies=jquery.ui.tabs,jquery.ui.button,jquery.effects.highlight,jquery.textSelection,mediawiki.util]|ProveIt-classic.css|ProveIt-classic.js
You must have appropriate permissions on destination wiki (including the right to edit system messages) and import from file uploads must be enabled.