Sets the function used for filtering items.
If @match_func is %NULL, the filter matches all items.
If the filter func changes its filtering behavior, gtk_filter_changed() needs to be called.
If a previous function was set, its @user_destroy will be called now.
function to filter items
user data to pass to @match_func
destroy notify for @user_data
See Implementation
Sets the function used for filtering items.
If @match_func is %NULL, the filter matches all items.
If the filter func changes its filtering behavior, gtk_filter_changed() needs to be called.
If a previous function was set, its @user_destroy will be called now.