Discussion already decided... *grrr*
The only way i was abel to find to quick fix T28221 and T28223, without rewritting the whole QmitChart and QmitkHistogramWidget (wich is currently out of question due to a lack of time), is by only using one fixed label name.
So at least this implicitly fixes T28206 somehow and decides the solution of this task.

The context menu actions are either not implemented or dysfunctional. Disable the context menu for now.

Closing as "invalid". The secret is to use the mouse wheel to navigate between time steps in the point set widget. It is not in sync with the Image Navigator. The whole plugin and widgets need a complete rewrite to actually work reliably with dynamic images, though, but this is out of scope for this task and the upcoming release.

I found several reasons to do a pseudo-UI test so I will come up with a draft for a test of the relevant classes.

Looked into it. So for quick fix we hace only the following options:

Thanks for the hint.

Ok, but then we can at least close T22391.

In T28203#218558, @kalali wrote:

Is this obsolete know with the discussion results stated in D459?

Most of the functions that can be called from the QmitkLevelWindowWidget (meaning the slider, the line edit and the contextmenu) are covered in mitkLevelWindowTest.
However, the LevelWindowManager tests where outdated and suboptimal, so I opened T28204.

Is this obsolete know with the discussion results stated in D459?

Ralf estimates that it takes a long time to fix this so we may come up with intermediate solutions or state in the UI that only 3d images are supported.

This is not high priority. Fix other release bugs before, please. :-)

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

probably related to T28206

It's definitely linked to the crosshair. If you disable the crosshair everything works immediately.

Zoom into the image until you have big pixels. Click in a pixel, crosshair snaps to that pixel, color/opacity is not shown. Click on that pixel again and it works. You can also click, hold, and move the cursor. As soon as you move the cursor it works. Stops working as soon as you leave the pixel and the crosshair snaps to the next pixel.

However, checking "Show Subchart" always invokes an update and then you can see it

Only happens in Windows installers. How do we debug this?

It is dependent of the crosshair position. If you do not see anything, carefully move the crosshair around in a 2d window and there is always at least a pixel or region, where the changes are visible. What is going on? 🐛

Wow, this is really a blocker. Didn't work in the December snapshot installer neither. Is it specific to installed versions maybe? I will try with a build-tree version...