Fix typo assuming new field value was always the name.

Fixes https://gitlab.com/kicad/code/kicad/issues/4936

eeschema/libedit/lib_edit_frame.h

@@ -321,13 +321,13 @@ private:
     bool LoadOneLibraryPartAux( LIB_PART* aLibEntry, const wxString& aLibrary, int aUnit,
                                 int aConvert );
 
+public:
     /**
      * Display the documentation of the selected component.
      */
     void DisplayCmpDoc();
 
     // General editing
-public:
     /**
      * Create a copy of the current component, and save it in the undo list.
      *

eeschema/tools/lib_edit_tool.cpp

@@ -503,9 +503,17 @@ void LIB_EDIT_TOOL::editFieldProperties( LIB_FIELD* aField )
     dlg.UpdateField( aField );
 
     if( renamed )
+    {
         parent->SetName( newFieldValue );
-
-    m_frame->UpdateAfterSymbolProperties( &oldFieldValue );
+        m_frame->UpdateAfterSymbolProperties( &oldFieldValue );
+    }
+    else
+    {
+        updateView( aField );
+        m_frame->GetCanvas()->Refresh();
+        m_frame->OnModify();
+        m_frame->DisplayCmpDoc();
+    }
 }