File/dir dialog styles and other changes (patch 1488371):

- check invalid combinations of styles in wxFileDialogBase::Create()
- use wxFD_XXX naming convention for wxFileDialog styles
- replaces wxDD_NEW_DIR_BUTTON with wxDD_DIR_MUST_EXIST
- removes #ifdef __WXGTK24__ / #endif blocks from wxGTK code
- removes wxFileDialogBase::Get/SetStyle and wxFileDialogBase::m_fileName
- renames wxDirDialogGTK to wxDirDialog


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39402 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/msw/dirdlg.cpp

@@ -148,7 +148,7 @@ int wxDirDialog::ShowModal()
     // is also the only way to have a resizable dialog
     //
     // "new" style is only available in the version 5.0+ of comctl32.dll
-    const bool needNewDir = HasFlag(wxDD_NEW_DIR_BUTTON);
+    const bool needNewDir = !HasFlag(wxDD_DIR_MUST_EXIST);
     if ( (needNewDir || HasFlag(wxRESIZE_BORDER)) && (verComCtl32 >= 500) )
     {
         if (needNewDir)