File filter not compatible with the standard tk filedialog

[ajeb78]

In tkFileBrowser it is necessary to specify file filters as e.g. filefilter=[("FITS files", "*.fit|*.fits"), ("All files", "*.*")] whereas the same filter for a standard tk filedialog would be filefilter=[("FITS files", "*.fit *.fits"), ("All files", "*.*")]

(The separator between multiple file extensions is a | instead of a space.)

This makes it much more awkward to use as a drop-in replacement. (My use case is that I'm writing a cross-platform script, and I'm quite happy with the way TK uses the native filedialogs on Windows and Mac, but on Linux the TK filedialog is astonishingly ugly and slow, so I want to use tkFileBrowser as a replacement on Linux but leave the native filedialogs on the other OSes. It should be a matter of:

if sys.platform.startswith("linux"):
    import tkfilebrowser as filedialog
else:
    from tkinter import filedialog

but it's made more complicated than it needs to be owing to have to handle the filter specifications differently.