FilterListModel.getPending

Returns the number of items that have not been filtered yet.

You can use this value to check if self is busy filtering by comparing the return value to 0 or you can compute the percentage of the filter remaining by dividing the return value by the total number of items in the underlying model:

pending = gtk_filter_list_model_get_pending (self);
model = gtk_filter_list_model_get_model (self);
percentage = pending / (double) g_list_model_get_n_items (model);

If no filter operation is ongoing - in particular when [gtk.filter_list_model.FilterListModel.incremental] is false - this function returns 0.