message: Fix incorrect parent of a control in FileViewer
  This caused an assert with wxGTK 3.1.6, which checks for this kind of
  mistakes.
  Fixes
diff: @@ -136,7 +136,7 @@ FileViewer::FileViewer(wxWindow*)
  #endif
  m_topBarSizer->Add(m_openInEditor, wxSizerFlags().Center().ReserveSpaceEvenIfHidden().Border(wxLEFT, PX(10)));
  - sizer->Add(new wxStaticLine(this, wxID_ANY, wxDefaultPosition, wxSize(-1, 1)), wxSizerFlags().Expand().Border(wxLEFT|wxRIGHT, PX(5)));
  + sizer->Add(new wxStaticLine(panel, 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);
  