message: Avoid flicker switching between error and reference views
diff: @@ -119,25 +119,22 @@ FileViewer::FileViewer(wxWindow*)
  SetIcons(wxIconBundle(wxStandardPaths::Get().GetResourcesDir() + "\\Resources\\Poedit.ico"));
  #endif
  - m_topBarSizer = new wxBoxSizer(wxVERTICAL);
  - sizer->Add(m_topBarSizer, wxSizerFlags().Expand());
  -
  - wxSizer *barsizer = new wxBoxSizer(wxHORIZONTAL);
  - m_topBarSizer->Add(barsizer, wxSizerFlags(1).Expand().Border(wxALL, PX(10)));
  + m_topBarSizer = new wxBoxSizer(wxHORIZONTAL);
  + sizer->Add(m_topBarSizer, wxSizerFlags().ReserveSpaceEvenIfHidden().Expand().Border(wxALL, PX(10)));
  m_file = new wxChoice(panel, wxID_ANY, wxDefaultPosition, wxSize(PX(300), -1));
  - barsizer->Add(m_file, wxSizerFlags().Center());
  + m_topBarSizer->Add(m_file, wxSizerFlags().Center().ReserveSpaceEvenIfHidden());
  m_description = new SecondaryLabel(panel, "");
  - barsizer->Add(m_description, wxSizerFlags(1).Center().PXBorder(wxLEFT|wxRIGHT));
  + m_topBarSizer->Add(m_description, wxSizerFlags(1).Center().PXBorder(wxLEFT|wxRIGHT));
  m_openInEditor = new wxButton(panel, wxID_ANY, MSW_OR_OTHER(_("Open in editor"), _("Open in Editor")));
  #ifdef __WXOSX__
  static_cast<NSButton*>(m_openInEditor->GetHandle()).bezelStyle = NSRoundRectBezelStyle;
  #endif
  - barsizer->Add(m_openInEditor, wxSizerFlags().Center().Border(wxLEFT, PX(10)));
  + m_topBarSizer->Add(m_openInEditor, wxSizerFlags().Center().ReserveSpaceEvenIfHidden().Border(wxLEFT, PX(10)));
  - m_topBarSizer->Add(new wxStaticLine(this, wxID_ANY, wxDefaultPosition, wxSize(-1, 1)), wxSizerFlags().Expand().Border(wxLEFT|wxRIGHT, PX(5)));
  + sizer->Add(new wxStaticLine(this, wxID_ANY, wxDefaultPosition, wxSize(-1, 1)), wxSizerFlags().Expand().Border(wxLEFT|wxRIGHT, PX(5)));
  m_content = wxWebView::New(panel, wxID_ANY);
  sizer->Add(m_content, 1, wxEXPAND);
  