data viewer - slice metadata

Metadata always display the delta / beta label. But paganin can be off. In this case we should hide it.

added enhancement label

changed milestone to %1.3

changed milestone to %1.4

added high priority low complexity labels

removed high priority label

added medium priority label

added For beginners label

ping @pautran

Some hint for beginners:

• setVolumeMetadata is called when metadata are set. Then it call _setDeltaBeta
• The dictionary metadata is expected to contain the phase/method key that allows us to know if we are using Paganin (or CTF - in this case we also want to display the delta / beta value)

So to fix this issue there is (at least) two ways to fix it:

• (a) when setting delta / beta we check the phase method. If the method is None then either
  • (1) we hide the _deltaBetaQLE widget
  • (2) or we set a string like '-' to mark the fact that we are not using it.
• (b) connecting the qt signal currentTextChanged from '_paganinQLE' to a callback displaying or not the _deltaBetaQLE widget; Then either (1) or (2) should be done

(b) might be more complicated but way more robust and in Qt spirit. no strong opinion between (1) and (2). The goal is to remove confusion about paganin being active or not. For now we display existing values even if no paganin (o CTF) used.

note on hidding _deltaBetaQLE

if we want to hide the _deltaBetaQLE at the moment it will only hide the widget and not the assocaited label 'δ/β'. What can be done with the [QFormLayout](https://doc.qt.io/qt-6/qformlayout.html) is to provide a widget instead of the 'row name' as a string. A QLabel in this case.

So instead of having

self.layout().addRow(" / ".join((DELTA_CHAR, BETA_CHAR)), self._deltaBetaQLE)

We have something like:

self._deltaBetaLabel = qt.QLabel(" / ".join((DELTA_CHAR, BETA_CHAR))
self.layout().addRow(self._deltaBetaLabel, self._deltaBetaQLE)

And now self._deltaBetaLabel can be hidden synchronously with self._deltaBetaQLE

assigned to @pautran

mentioned in commit 46371771