Plugins: Needs more aggresive advertisment of widget factory

[jzaefferer]

While there is a using-widget-factory tutorial, the previous two plugin authoring guides, along with the category page, don't mention the widget factory at all. We need more aggresive advertising of the widget factory in all three, at least once per page.

[arthurvr]

Sure 👍 I will probably get to it, but if somebody has the time right now, feel free :)

[fnagel]

Perhaps a section comparing both ways of creating stateful plugins including an explanation why using the Widget Factory is a good idea would be helpful.