Cycled widget styles (such as the battery charging style) were broken
until now. The reason for this: They maintain state that represents the
current cycle position (i.e. what is the current icon that is being
displayed), but that is done in a way that uses repr() on the widget
object.
Since the widget objects are re-created each time the bar is drawn, this
is a deeply flawed design.
Instead, use the instance() of the widget for now.