2 files changed, 13 insertions, 6 deletions

diff --git a/protocols/wlr-layer-shell-unstable-v1.xml b/protocols/wlr-layer-shell-unstable-v1.xml
index 3181c0bb..6a5d5d35 100644
--- a/protocols/wlr-layer-shell-unstable-v1.xml
+++ b/protocols/wlr-layer-shell-unstable-v1.xml
@@ -47,12 +47,16 @@
         or manipulate a buffer prior to the first layer_surface.configure call
         must also be treated as errors.
 
+        You may pass NULL for output to allow the compositor to decide which
+        output to use. Generally this will be the one that the user most
+        recently interacted with.
+
         Clients can specify a namespace that defines the purpose of the layer
         surface.
       </description>
       <arg name="id" type="new_id" interface="zwlr_layer_surface_v1"/>
       <arg name="surface" type="object" interface="wl_surface"/>
-      <arg name="output" type="object" interface="wl_output"/>
+      <arg name="output" type="object" interface="wl_output" allow-null="true"/>
       <arg name="layer" type="uint" enum="layer" summary="layer to add this surface to"/>
       <arg name="namespace" type="string" summary="namespace for the layer surface"/>
     </request>
diff --git a/swaybg/main.c b/swaybg/main.c
index 679b8c20..5b6c378c 100644
--- a/swaybg/main.c
+++ b/swaybg/main.c
@@ -113,7 +113,7 @@ static void layer_surface_closed(void *data,
         state->run_display = false;
 }
 
-struct zwlr_layer_surface_v1_listener layer_surface_listener = {
+static const struct zwlr_layer_surface_v1_listener layer_surface_listener = {
         .configure = layer_surface_configure,
         .closed = layer_surface_closed,
 };
@@ -141,7 +141,7 @@ static void output_scale(void *data, struct wl_output *output, int32_t factor) {
         }
 }
 
-struct wl_output_listener output_listener = {
+static const struct wl_output_listener output_listener = {
         .geometry = output_geometry,
         .mode = output_mode,
         .done = output_done,
@@ -203,7 +203,8 @@ int main(int argc, const char **argv) {
                 return 1;
         }
 
-        assert(state.display = wl_display_connect(NULL));
+        state.display = wl_display_connect(NULL);
+        assert(state.display);
 
         struct wl_registry *registry = wl_display_get_registry(state.display);
         wl_registry_add_listener(registry, &registry_listener, &state);
@@ -213,9 +214,11 @@ int main(int argc, const char **argv) {
         // Second roundtrip to get output properties
         wl_display_roundtrip(state.display);
 
-        assert(state.surface = wl_compositor_create_surface(state.compositor));
+        state.surface = wl_compositor_create_surface(state.compositor);
+        assert(state.surface);
 
-        assert(state.input_region = wl_compositor_create_region(state.compositor));
+        state.input_region = wl_compositor_create_region(state.compositor);
+        assert(state.input_region);
         wl_surface_set_input_region(state.surface, state.input_region);
 
         state.layer_surface = zwlr_layer_shell_v1_get_layer_surface(