No, I'm still using this ugly and clumsy widget... I don't think there's an easily available better option.
As far as creating a new subdirectory, the chooseDirectory returns a path, you create the directory. Parts of my code look something like this:

my $folder;

# in real code this is triggered by a button press
$folder = $mw->chooseDirectory(    -initialdir => '~', -title => 'Choo
+se a folder',);


# triggered after user made its folder choice
# almost certainly won't work if user enters a multi-level folder stru
+cture
if (!-d "$folder") {
    print "\nCreating $folder";
    mkdir "$folder" or abort("Can't create folder $folder: $! at line 
+" . __LINE__);  # abort sub is my own code, use die if needed
}
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