[link_specular] Fix linking data to specular instrument (#544) ()

Merging branch 'link_specular'  into 'r20.0'.

See merge request !1517

GUI/Model/Device/InstrumentItems.cpp

@@ -401,16 +401,10 @@ bool SpecularInstrumentItem::alignedWith(const RealItem* item) const
     if (!item->hasNativeData())
         return false;
 
-    // TODO do not compare native axis with main data axis due to different units
-    // remove native data from everywhere
+    // TODO remove native data from everywhere
     // https://jugit.fz-juelich.de/mlz/bornagain/-/issues/331
-    //
-    //    const auto& native_axis = item->nativeDatafield()->axis(0);
-    //    return *instrumentAxis == native_axis;
-    //
-    // compare instrument axis with the main data axis instead
-    const auto& data_axis = item->dataItem()->datafield()->axis(0);
-    return *instrumentAxis == data_axis;
+    const auto& native_axis = item->nativeDatafield()->axis(0);
+    return *instrumentAxis == native_axis;
 }
 
 const ICoordSystem* SpecularInstrumentItem::createCoordSystem() const

GUI/View/Instrument/AlphaScanEditor.cpp

@@ -52,10 +52,10 @@ AlphaScanEditor::AlphaScanEditor(QWidget* parent, GrazingScanItem* item)
     gform->addRow(m_selector);
 
     //... update axis type combo (needs m_form)
-    if (idx != typeComboBox->currentIndex())
+    if (idx != typeComboBox->currentIndex()) {
         typeComboBox->setCurrentIndex(idx);
-    else
-        onAxisTypeSelected(idx); // trigger update manually
+        onAxisTypeSelected(idx);
+    }
     typeComboBox->setEnabled(m_item->pointwiseAlphaAxisDefined());
     connect(typeComboBox, qOverload<int>(&QComboBox::currentIndexChanged), this,
             &AlphaScanEditor::onAxisTypeSelected);