A function which decides whether the row indicated by @iter matches
a given @key, and should be displayed as a possible completion for @key.
Note that @key is normalized and case-folded (see g_utf8_normalize()
and g_utf8_casefold()). If this is not appropriate, match functions
have access to the unmodified key via
gtk_editable_get_text (GTK_EDITABLE (gtk_entry_completion_get_entry ())).
A function which decides whether the row indicated by @iter matches a given @key, and should be displayed as a possible completion for @key.
Note that @key is normalized and case-folded (see g_utf8_normalize() and g_utf8_casefold()). If this is not appropriate, match functions have access to the unmodified key via gtk_editable_get_text (GTK_EDITABLE (gtk_entry_completion_get_entry ())).