A report is defined by its data, but this is not enough.
We also need to somehow define in the report
Also see #5546
This has to be specified first as I think I may have forgotten some points.
(In ) - API CHANGE: the API for the function Piwik_AddWidget has changed. The new API is Piwik_AddWidget( $widgetCategory, $widgetName, $controllerName, $controllerAction, $customParameters = array()). See examples of calls in all the core Piwik plugins. This change was necessary to make widgets more modular (they now accept custom parameters).
ADDED: now widgets can be created with custom parameters. This makes it possible to create a widget that calls a controller->action with other custom parameters, this is used in Piwik to draw an evolution graph (module=VisitsSummary & action=getEvolutionGraph) for a given metric (&columns=nb_visits). These custom parameters are automatically forwarded to the sparkline url, the flash graph when clicked on sparkline, etc.
The widget layout is now saved as a JSON string rather than a custom data structure. The dashboard code should be able to read & restore most of the layouts from the old format (except the evolution graphs widgets). Simplified the Dashboard.js, widgetMenu.js, cleaned up what was a messy code.