no default filename will be supplied. The wildcard determines what files
are displayed in the file selector, and file extension supplies a type
extension for the required filename. Flags may be a combination of wxOPEN,
-wxSAVE, wxOVERWRITE\_PROMPT, wxHIDE\_READONLY, wxMULTIPLE or 0.
+wxSAVE, wxOVERWRITE\_PROMPT, wxHIDE\_READONLY, wxFILE\_MUST\_EXIST, wxMULTIPLE or 0.
Both the X and Windows versions implement a wildcard filter. Typing a
filename containing wildcards (*, ?) in the filename text item, and