char* gtk_entry_completion_compute_prefix ( GtkEntryCompletion* completion, const char* key )
Computes the common prefix that is shared by all rows in
that start with
If no row matches
NULL will be returned.
Note that a text column must have been set for this function to work,
gtk_entry_completion_set_text_column() for details.
The text to complete for.
|The data is owned by the caller of the function.|
|The value is a NUL terminated UTF-8 string.|