gtk_file_chooser_set_filter() doesn't work for GtkFileChooserNative. The
code forwards added and removed filters to the delegate dialog, but
doesn't do anything to set the selected one, so the wrong one gets
chosen. So fix that.
This only fixes the fallback dialog. The portal will be fixed in a
subsequent commit.
Partial fix for #1492
case GTK_FILE_CHOOSER_PROP_FILTER:
self->current_filter = g_value_get_object (value);
+ gtk_file_chooser_set_filter (GTK_FILE_CHOOSER (self->dialog), self->current_filter);
g_object_notify (G_OBJECT (self), "filter");
break;