Is there a way to add multiple filemasks in wx.lib.filebrowsebutton.FileBrowseButton?

Is there a way to add multiple filemasks in
wx.lib.filebrowsebutton.FileBrowseButton?

I'm trying to make a wx.lib.filebrowsebutton.FileBrowseButton button match
both txt and csv files, but it doesn't seem to support glob pattern as
described, *.{txt,csv} ends up matching nothing on windows and it
literally tries to look for files with extension of {txt,csv}.
So how do I make it work for both txt and csv files?