[TD]Fix auto correct msg missing16892 (#16909)

* [TD]fix bad return code on auto-correct fail

* [TD]prevent changing references in property editor

- this is a "shoot yourself in the foot" practice

src/Mod/TechDraw/App/DrawViewDimension.cpp

@@ -206,6 +206,9 @@ DrawViewDimension::DrawViewDimension()
         (App::Prop_None),
         "Feature bounding box corners as of last reference update.  Used by autocorrect");
 
+    // changing the references in the property editor will only cause problems
+    References2D.setStatus(App::Property::ReadOnly, true);
+    References3D.setStatus(App::Property::ReadOnly, true);
 
     // hide the DrawView properties that don't apply to Dimensions
     ScaleType.setStatus(App::Property::ReadOnly, true);
@@ -464,8 +467,7 @@ App::DocumentObjectExecReturn* DrawViewDimension::execute()
         m_referencesCorrect = autocorrectReferences();
     }
     if (!m_referencesCorrect) {
-        m_referencesCorrect = true;
-        new App::DocumentObjectExecReturn("Autocorrect failed to fix broken references", this);
+        return new App::DocumentObjectExecReturn("Autocorrect failed to fix broken references", this);
     }
 
     // references are good, we can proceed