diff --git a/cage.c b/cage.c
index e4eb90f..541c1c2 100644
--- a/cage.c
+++ b/cage.c
@@ -270,6 +270,8 @@ main(int argc, char *argv[])
 		return 1;
 	}
 
+	server.output_mode = CAGE_MULTI_OUTPUT_MODE_EXTEND;
+
 #ifdef DEBUG
 	wlr_log_init(WLR_DEBUG, NULL);
 #else
diff --git a/server.h b/server.h
index 5caa0c1..401dd55 100644
--- a/server.h
+++ b/server.h
@@ -16,6 +16,11 @@
 #include "seat.h"
 #include "view.h"
 
+enum cg_multi_output_mode {
+	CAGE_MULTI_OUTPUT_MODE_EXTEND,
+	CAGE_MULTI_OUTPUT_MODE_LAST,
+};
+
 struct cg_server {
 	struct wl_display *wl_display;
 	struct wl_list views;
@@ -26,6 +31,7 @@ struct cg_server {
 	struct wl_listener new_idle_inhibitor_v1;
 	struct wl_list inhibitors;
 
+	enum cg_multi_output_mode output_mode;
 	struct wlr_output_layout *output_layout;
 	struct wl_list outputs;
 	struct wl_listener new_output;