Fix some issues with zooming.

Don't process zoom both in Legacy code and Modern code; one of
them will decide the zoom has already changed and do odd things.

Make sure the view is updated after zooming, otherwise you have
to move the mouse over the canvas before seeing the new zoom.

common/draw_frame.cpp

@@ -524,28 +524,23 @@ void EDA_DRAW_FRAME::OnSelectZoom( wxCommandEvent& event )
     if( id < 0 || !( id < (int)m_zoomSelectBox->GetCount() ) )
         return;
 
-    if( id == 0 )                      // Auto zoom (Fit in Page)
+    if( IsGalCanvasActive() )
+    {
+        m_toolManager->RunAction( "common.Control.zoomPreset", true, id );
+        UpdateStatusBar();
+        m_galCanvas->Refresh();
+    }
+    else if( id == 0 )                      // Auto zoom (Fit in Page)
     {
         Zoom_Automatique( true );
+        m_canvas->Refresh();
     }
     else
     {
         double selectedZoom = GetScreen()->m_ZoomList[id-1];
 
-        if( GetScreen()->GetZoom() == selectedZoom )
-            return;
-
-        GetScreen()->SetZoom( selectedZoom );
-        RedrawScreen( GetScrollCenterPosition(), false );
-    }
-
-    // Notify GAL
-    TOOL_MANAGER* mgr = GetToolManager();
-
-    if( mgr && IsGalCanvasActive() )
-    {
-        mgr->RunAction( "common.Control.zoomPreset", true, id );
-        UpdateStatusBar();
+        if( GetScreen()->SetZoom( selectedZoom ) )
+            RedrawScreen( GetScrollCenterPosition(), false );
     }
 }