Similar to T28223: [ImageStatistics] Deleting a datanode after statistics leads to no histogram update for the next node.

This is quickfixed with T28221. I keep the task open and move it to the next milestone, as the quickfix does hide the problem, but it should be handled as soon as we want to display node names in the histogram legend again. The proper fix would be to listen to changes of the node(s) that is displayed in the histogram widget and to update the labeling as soon has the name property of the node has changed.

I tried to reproduce this issue and found the following:
With the changes in T28211 @floca mentioned, there is no legend anymore m_Controls.chartWidget->SetShowLegend(false);
Showing this legend again displays "histogram" as the label name - not even the original segmentation node name. Now when I add another segmentation and add it to the statistics, the histogram is completely removed (it's calculated but the widget does not provide any space for the histogram anymore).

Also: When using a segmentation without any label the log says

459.42 core.mod.imgStatUi.imgStatCalculationrunnable ERROR: Failure while calculating the statistics: MITK-dev\src\Modules\ImageStatistics\mitkImageStatisticsCalculator.cpp:165:
unknown label
460.60 WARNING: Error when calculating statistics: Error while running computation. Error description: Failure while calculating the statistics: MITK-dev\src\Modules\ImageStatistics\mitkImageStatisticsCalculator.cpp:165:
unknown label

without giving any hint on the workbench UI. Only the hourglass won't disappear.

So actually the whole histogram is not working at all, as far as I can see. Where do we start? :D

In T28206#223651, @kalali wrote:

With the changes in T28211 @floca mentioned,

You meen T28221, don't you?

Sorry I was not very precise in my comment above (https://phabricator.mitk.org/T28206#219094). To solve that issue we have also to solve T27284.

After reevaluating the goal of this task, I think I have made an categorization error. This is more a statistic task then a segmentation task. So I would propose to postpone it and take it from the active columns (and move it into the backlog or next milestone again) as it is not part of our current cycle focus topics.