Fixes session lock surfaces not being able to switch focused output

include/sway/server.h

@@ -178,6 +178,8 @@ void sway_session_lock_add_output(struct sway_session_lock *lock,
 	struct sway_output *output);
 bool sway_session_lock_has_surface(struct sway_session_lock *lock,
 	struct wlr_surface *surface);
+void sway_session_lock_focus_output(struct sway_session_lock *lock,
+	struct sway_output *output);
 void handle_xdg_shell_toplevel(struct wl_listener *listener, void *data);
 #if WLR_HAS_XWAYLAND
 void handle_xwayland_surface(struct wl_listener *listener, void *data);

sway/input/seat.c

@@ -1273,6 +1273,24 @@ void seat_set_focus(struct sway_seat *seat, struct sway_node *node) {
 		seat_set_workspace_focus(seat, node);
 	}
 	if (server.session_lock.lock) {
+		struct sway_output *output = NULL;
+		if (node != NULL) {
+			switch (node->type) {
+			case N_OUTPUT:
+				output = node->sway_output;
+				break;
+			case N_WORKSPACE:
+				output = node->sway_workspace->output;
+				break;
+			default:
+				break;
+			}
+		}
+		if (output != NULL) {
+			sway_session_lock_focus_output(server.session_lock.lock, output);
+			return;
+		}
+		// Fallback to the previously focused lock surface
 		seat_set_focus_surface(seat, server.session_lock.lock->focused, false);
 	}
 }

sway/lock.c

@@ -8,6 +8,7 @@
 #include "sway/layers.h"
 #include "sway/output.h"
 #include "sway/server.h"
+#include "sway/tree/workspace.h"
 #include "sway/lock.h"
 
 struct sway_session_lock_output {
@@ -59,9 +60,34 @@ static void refocus_output(struct sway_session_lock_output *output) {
 	}
 }
 
+void sway_session_lock_focus_output(struct sway_session_lock *lock,
+	struct sway_output *output) {
+	// Try focusing the lock surface on the provided output
+	struct sway_session_lock_output *candidate;
+	wl_list_for_each(candidate, &lock->outputs, link) {
+		if (candidate->output != output || !candidate->surface) {
+			continue;
+		}
+
+		if (candidate->surface->surface->mapped) {
+			// Set the focus for all seats
+			focus_surface(lock, candidate->surface->surface);
+			break;
+		}
+	}
+}
+
 static void handle_surface_map(struct wl_listener *listener, void *data) {
 	struct sway_session_lock_output *surf = wl_container_of(listener, surf, surface_map);
-	if (surf->lock->focused == NULL) {
+
+	struct sway_seat *seat = input_manager_current_seat();
+	struct sway_workspace *focused_ws = seat_get_focused_workspace(seat);
+	struct sway_output *focused_output = NULL;
+	if (focused_ws != NULL) {
+		focused_output = focused_ws->output;
+	}
+
+	if (surf->lock->focused == NULL || focused_output == surf->output) {
 		focus_surface(surf->lock, surf->surface->surface);
 	}
 	cursor_rebase_all();