Specifying file:// object handling apps. in HyperLinkCtrl

Hi, folks! Working from the HyperLinkCtrl demo, through trial and error, I've determined that wx.lib.hyperlink.HyperLinkCtrl.GoToUrl is able to open some file:// objects (e.g., directories, .txt, .exe on Windows) but not others (at least not the way I'm configured). Since I haven't made any specifications in this regard, I conclude that default use is being made of system-level extension-application associations. How can I provide such specifications programatically? Thanks!

DG