Visualforce pages can be used as dashboard components. A dashboard shows data from source report as visual component and each dashboard can have up to 20 components. Visualforce pages that use the standard controller can’t be used in dashboards. To be included in a dashboard, a Visualforce page must have either no controller, use a custom controller, or reference a page bound to the StandardSetController Class.
If a Visualforce page does not meet these requirements, it does not appear as an option in the dashboard component Visualforce Page drop-down list.
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