Tried to fix it but couldn't without putting a lot of work into a proper solution (probably days, weeks!?!) The problem is kinda in the nature of how Piwik works right now. Could be probably easily fixed once visualizations use AngularJS.

The problem is the following: The first time the evolution is requested this is done with VisitsSummary.index action. Once you click on a sparkline the updated evolution is requested via VisitsSummary.getEvolutionGraph. This action/URL is not registered in the menu and therefore it cannot build the URL to reload the same page here:
https://github.com/piwik/piwik/blob/master/plugins/CoreVisualizations/JqplotDataGenerator/Evolution.php#L169

I thought about workarounds and tried different solutions but the only one that could work would be to always hardcoded replace the module/action in the URL to open with the current module/action from the URL (retrieved via broadcast.getValueFromHash()) here: https://github.com/piwik/piwik/blob/master/plugins/CoreVisualizations/javascripts/jqplotEvolutionGraph.js#L92 . This would mean the evolution would always reload the same page, even if you want a different behavior. This component should not have such knowledge and is rather bad design since you would not expect this (it should exactly open the passed URL and not modify it) but it would be maybe ok if we always want this behavior. Of course we would in this case make the decision also for plugin developers.

@tsteur
Thanks for detailed explanation! It's rather rare case so perhaps we can leave it for now if it's too time consuming.

I thought about workarounds and tried different solutions but the only one that could work would be to always hardcoded replace the module/action in the URL to open with the current module/action

this sounds like a fine solution to always redirect the user to the currently viewed module/action - @tsteur maybe this is appropriate solution to this issue?

(ie. it's better to redirect always to current module/action rather than redirect to dashboard)

Yeah, we just have to be aware that any other behavior won't be possible anymore afterwards as it is a hack. Even for plugin developers who maybe want a different behavior as the widget could be used in many different ways... I think it would be maybe not necessarily a bug if we would always redirect to the dashboard but sometimes this and sometimes an other behavior is a bug. We can add the hack now and remove it once we rewrite the visualizations with Angular JS.

sometimes this and sometimes an other behavior is a bug.

+1

the question is whether it is better to:

1. redirect always to dashboard
2. redirect always to current module/action

I vote for 2) @tsteur does it make sense?

yes

Should work. Feel free to reopen in case of any issues