use initialized for complete init() function

not only for the feature part

src/gui/editorwidgets/qgsrelationreferencewidget.cpp

@@ -460,8 +460,8 @@ void QgsRelationReferenceWidget::showEvent( QShowEvent *e )
   Q_UNUSED( e )
 
   mShown = true;
-
-  init();
+  if ( !mInitialized )
+    init();
 }
 
 void QgsRelationReferenceWidget::init()
@@ -555,14 +555,12 @@ void QgsRelationReferenceWidget::init()
 
     // Only connect after iterating, to have only one iterator on the referenced table at once
     connect( mComboBox, static_cast<void ( QComboBox::* )( int )>( &QComboBox::currentIndexChanged ), this, &QgsRelationReferenceWidget::comboReferenceChanged );
+    //call it for the first time
+    emit mComboBox->currentIndexChanged( mComboBox->currentIndex() );
 
-    if ( !mFeatureInitialized )
-    {
-      //call it for the first initialization
-      emit mComboBox->currentIndexChanged( mComboBox->currentIndex() );
-      mFeatureInitialized = true;
-    }
     QApplication::restoreOverrideCursor();
+
+    mInitialized = true;
   }
 }
 

src/gui/editorwidgets/qgsrelationreferencewidget.h

@@ -222,7 +222,7 @@ class GUI_EXPORT QgsRelationReferenceWidget : public QWidget
     bool mIsEditable = true;
     QStringList mFilterFields;
     QMap<QString, QMap<QString, QSet<QString> > > mFilterCache;
-    bool mFeatureInitialized = false;
+    bool mInitialized = false;
 
     // Q_PROPERTY
     bool mEmbedForm = false;