diff --git a/eeschema/tool_viewlib.cpp b/eeschema/tool_viewlib.cpp
index be64896b42..17b967ea3a 100644
--- a/eeschema/tool_viewlib.cpp
+++ b/eeschema/tool_viewlib.cpp
@@ -41,7 +41,6 @@
 void LIB_VIEW_FRAME::ReCreateHToolbar()
 {
     wxString    msg;
-    LIB_PART*   part = NULL;
 
     if( m_mainToolBar )
         m_mainToolBar->Clear();
@@ -119,33 +118,6 @@ void LIB_VIEW_FRAME::ReCreateHToolbar()
     // reflect the changes
     m_mainToolBar->Realize();
 
-    if( m_libraryName.size() && m_entryName.size() )
-    {
-        if( Prj().SchSymbolLibTable()->HasLibrary( m_libraryName ) )
-        {
-            part = GetLibPart( LIB_ID( m_libraryName, m_entryName ) );
-        }
-    }
-
-    /// @todo Move updating the symbol units in the combobox to the symbol select function
-    ///       and stop calling this function to update the toolbar.  All of the other toolbar
-    ///       updates are handled by wxUpdateUIEvents.
-    int parts_count = 1;
-
-    if( part )
-        parts_count = std::max( part->GetUnitCount(), 1 );
-
-    m_selpartBox->Clear();
-
-    for( int ii = 0; ii < parts_count; ii++ )
-    {
-        msg.Printf( _( "Unit %c" ), 'A' + ii );
-        m_selpartBox->Append( msg );
-    }
-
-    m_selpartBox->SetSelection( m_unit > 0 ? m_unit - 1 : 0 );
-    m_selpartBox->Enable( parts_count > 1 );
-
     m_mainToolBar->Refresh();
 }
 
diff --git a/eeschema/viewlib_frame.cpp b/eeschema/viewlib_frame.cpp
index b768f80823..3419c6eff0 100644
--- a/eeschema/viewlib_frame.cpp
+++ b/eeschema/viewlib_frame.cpp
@@ -87,6 +87,7 @@ BEGIN_EVENT_TABLE( LIB_VIEW_FRAME, EDA_DRAW_FRAME )
     EVT_UPDATE_UI( ID_LIBVIEW_DE_MORGAN_CONVERT_BUTT,
                    LIB_VIEW_FRAME::onUpdateAlternateBodyStyleButton )
     EVT_UPDATE_UI( ID_LIBVIEW_SHOW_ELECTRICAL_TYPE, LIB_VIEW_FRAME::OnUpdateElectricalType )
+    EVT_UPDATE_UI( ID_LIBVIEW_SELECT_PART_NUMBER, LIB_VIEW_FRAME::OnUpdateSelectionPartBox )
 
 END_EVENT_TABLE()
 
@@ -367,6 +368,45 @@ void LIB_VIEW_FRAME::OnUpdateElectricalType( wxUpdateUIEvent& aEvent )
 }
 
 
+void LIB_VIEW_FRAME::OnUpdateSelectionPartBox( wxUpdateUIEvent& aEvent )
+{
+    LIB_PART* part = nullptr;
+
+    if( m_libraryName.size() && m_entryName.size() )
+    {
+        if( Prj().SchSymbolLibTable()->HasLibrary( m_libraryName ) )
+            part = GetLibPart( LIB_ID( m_libraryName, m_entryName ) );
+    }
+
+    int unit_count = 1;
+
+    if( part )
+        unit_count = std::max( part->GetUnitCount(), 1 );
+
+    m_selpartBox->Enable( unit_count > 1 );
+
+    if( unit_count > 1 )
+    {
+        // rebuild the unit list if it is not suitable
+        if( unit_count != (int)m_selpartBox->GetCount() )
+        {
+            m_selpartBox->Clear();
+
+            for( int ii = 0; ii < unit_count; ii++ )
+
+                m_selpartBox->Append( wxString::Format( _( "Unit %c" ), 'A' + ii ) );
+
+            m_selpartBox->SetSelection( m_unit > 0 ? m_unit - 1 : 0 );
+        }
+    }
+    else
+    {
+        if( m_selpartBox->GetCount() )
+            m_selpartBox->Clear();
+    }
+}
+
+
 double LIB_VIEW_FRAME::BestZoom()
 {
     LIB_PART*   part = NULL;
@@ -475,7 +515,6 @@ bool LIB_VIEW_FRAME::ReCreateListLib()
     }
 
     bool cmp_changed = ReCreateListCmp();
-    ReCreateHToolbar();
     DisplayLibInfos();
     m_canvas->Refresh();
 
@@ -555,7 +594,6 @@ void LIB_VIEW_FRAME::SetSelectedLibrary( const wxString& aLibraryName )
     ReCreateListCmp();
     m_canvas->Refresh();
     DisplayLibInfos();
-    ReCreateHToolbar();
 
     // Ensure the corresponding line in m_libList is selected
     // (which is not necessary the case if SetSelectedLibrary is called
@@ -598,7 +636,6 @@ void LIB_VIEW_FRAME::SetSelectedComponent( const wxString& aComponentName )
         }
 
         Zoom_Automatique( false );
-        ReCreateHToolbar();
         m_canvas->Refresh();
     }
 }
diff --git a/eeschema/viewlib_frame.h b/eeschema/viewlib_frame.h
index d873ef3f31..cd7882c9c4 100644
--- a/eeschema/viewlib_frame.h
+++ b/eeschema/viewlib_frame.h
@@ -171,6 +171,7 @@ private:
     void onUpdateNormalBodyStyleButton( wxUpdateUIEvent& aEvent );
     void onUpdateViewDoc( wxUpdateUIEvent& aEvent );
     void OnUpdateElectricalType( wxUpdateUIEvent& aEvent );
+    void OnUpdateSelectionPartBox( wxUpdateUIEvent& aEvent );
     void onSelectNextSymbol( wxCommandEvent& aEvent );
     void onSelectPreviousSymbol( wxCommandEvent& aEvent );
     void onViewSymbolDocument( wxCommandEvent& aEvent );