I am using piwik widgets to give an overview of visitors to our customers in their backend. But since I upgraded from 1.4 to 1.5.1, the VisitsSummary EvolutionGraph Widgets are not working anymore in Internet Explorer 7 and 8.
It shows the borders and controls of the graph but there is no grid and no graph which could be hovered.
The sites of our customers have anonymous view access and the non-graph widgets are working perfectly.
To reproduce, use an URL like:
Replace HOST and SITE_ID accordingly.
IE 8 throws:
Message: 'window.G_vmlCanvasManager' is null or not an object
Keywords: visitssummary, graph, widget, IE,
 refs #2582 - load excanvas before jqplot in Widgetize iframe