Please do so by passing an empty string in this parameter, the methods worked as well as without this parameter, that is, display filters by default.
Now is inconvenient - you have to write the conditions for the presence of a filter like this:
If Len(sFilters) = 0 Then
vResult = nuiws.OpenFileDialog(bMulty, sTitle,, sInitialDir, sInitialFile)
vResult = nuiws.OpenFileDialog(bMulty, sTitle, sFilters, sInitialDir, sInitialFile)
Also ask in these dialogs to display a field with the types-filters of files, as there is in of standard operating system file dialogs.