Add option to add outputs as choice boxes.

Alternative to emersion#60

main.c

@@ -741,7 +741,8 @@ int main(int argc, char *argv[]) {
 
 	int opt;
 	char *format = "%x,%y %wx%h";
-	while ((opt = getopt(argc, argv, "hdb:c:s:w:pf:")) != -1) {
+	bool output_boxes = false;
+	while ((opt = getopt(argc, argv, "hdb:c:s:w:pof:")) != -1) {
 		switch (opt) {
 		case 'h':
 			printf("%s", usage);
@@ -774,6 +775,9 @@ int main(int argc, char *argv[]) {
 		case 'p':
 			state.single_point = true;
 			break;
+		case 'o':
+			output_boxes = true;
+			break;
 		default:
 			printf("%s", usage);
 			return EXIT_FAILURE;
@@ -901,6 +905,16 @@ int main(int argc, char *argv[]) {
 	// second roundtrip for xdg-output
 	wl_display_roundtrip(state.display);
 
+	if (output_boxes) {
+		struct slurp_output *box_output;
+		wl_list_for_each(box_output, &state.outputs, link) {
+			add_choice_box(&state, &box_output->logical_geometry);
+			struct slurp_box *new_box;
+			new_box = wl_container_of(state.boxes.prev, new_box, link);
+			new_box->label = strdup(new_box->label); // to avoid double free
+		}
+	}
+
 	struct slurp_seat *seat;
 	wl_list_for_each(seat, &state.seats, link) {
 		seat->cursor_surface =