This is a problem of the evolution graph I encountered while developing a plugin with Piwik 1.8.2.
The problem is that an evolution graph with its footer disabled fails to process changes in the rows/columns to display.
To reproduce this bug, modify the method getEvolutionGraph in Piwik_Referers_Controller. After the first line where it creates the view with
$view = $this->getLastUnitGraph($this->pluginName, FUNCTION, 'Referers.getRefererType');
add the following line:
Open Piwik and go to Referers/Overview. Mouse over the Metrics/Records selection button and tick the Website checkbox.
The widget displays the loading animation but it fails to display the data.
Keywords: evolution graph disable footer
Disabling the footer shouldn't prevent non-footer features from working indeed, thanks for the report.
we shall fix it when it will be a core use case. if you have a patch, please send a pull request we would appreciate!