3 files changed, 73 insertions, 4 deletions

diff --git a/rootston/cursor.c b/rootston/cursor.c
index 1ee195c2..6fb2688c 100644
--- a/rootston/cursor.c
+++ b/rootston/cursor.c
@@ -271,6 +271,13 @@ static void roots_cursor_press_button(struct roots_cursor *cursor,
 			break;
 		case WLR_BUTTON_PRESSED:
 			roots_seat_set_focus(seat, view);
+			if (wlr_surface_is_layer_surface(surface)) {
+				struct wlr_layer_surface *layer =
+					wlr_layer_surface_from_wlr_surface(surface);
+				if (layer->current.keyboard_interactive) {
+					roots_seat_set_focus_layer(seat, layer);
+				}
+			}
 			break;
 		}
 	}
diff --git a/rootston/layer_shell.c b/rootston/layer_shell.c
index d3a91659..1cd93b3c 100644
--- a/rootston/layer_shell.c
+++ b/rootston/layer_shell.c
@@ -192,6 +192,33 @@ void arrange_layers(struct roots_output *output) {
 	arrange_layer(output->wlr_output,
 			&output->layers[ZWLR_LAYER_SHELL_V1_LAYER_BACKGROUND],
 			&usable_area, false);
+
+	// Find topmost keyboard interactive layer, if such a layer exists
+	uint32_t layers_above_shell[] = {
+		ZWLR_LAYER_SHELL_V1_LAYER_OVERLAY,
+		ZWLR_LAYER_SHELL_V1_LAYER_TOP,
+	};
+	size_t nlayers = sizeof(layers_above_shell) / sizeof(layers_above_shell[0]);
+	struct roots_layer_surface *layer, *topmost = NULL;
+	for (size_t i = 0; i < nlayers; ++i) {
+		wl_list_for_each_reverse(layer,
+				&output->layers[layers_above_shell[i]], link) {
+			if (layer->layer_surface->current.keyboard_interactive) {
+				topmost = layer;
+				break;
+			}
+		}
+		if (topmost != NULL) {
+			break;
+		}
+	}
+
+	struct roots_input *input = output->desktop->server->input;
+	struct roots_seat *seat;
+	wl_list_for_each(seat, &input->seats, link) {
+		roots_seat_set_focus_layer(seat,
+				topmost ? topmost->layer_surface : NULL);
+	}
 }
 
 static void handle_output_destroy(struct wl_listener *listener, void *data) {
diff --git a/rootston/seat.c b/rootston/seat.c
index bdcad5c7..cfdeab00 100644
--- a/rootston/seat.c
+++ b/rootston/seat.c
@@ -4,6 +4,7 @@
 #include <wayland-server.h>
 #include <wlr/config.h>
 #include <wlr/types/wlr_idle.h>
+#include <wlr/types/wlr_layer_shell.h>
 #include <wlr/types/wlr_xcursor_manager.h>
 #include <wlr/util/log.h>
 #include "rootston/cursor.h"
@@ -723,7 +724,6 @@ void roots_seat_set_focus(struct roots_seat *seat, struct roots_view *view) {
 		wl_list_insert(&seat->input->server->desktop->views, &view->link);
 	}
 
-
 	bool unfullscreen = true;
 
 #ifdef WLR_HAS_XWAYLAND
@@ -781,14 +781,18 @@ void roots_seat_set_focus(struct roots_seat *seat, struct roots_view *view) {
 		return;
 	}
 
-	view_activate(view, true);
-
-	seat->has_focus = true;
 	wl_list_remove(&seat_view->link);
 	wl_list_insert(&seat->views, &seat_view->link);
 
 	view_damage_whole(view);
 
+	if (seat->focused_layer) {
+		return;
+	}
+
+	view_activate(view, true);
+	seat->has_focus = true;
+
 	struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->seat);
 	if (keyboard != NULL) {
 		wlr_seat_keyboard_notify_enter(seat->seat, view->wlr_surface,
@@ -800,6 +804,37 @@ void roots_seat_set_focus(struct roots_seat *seat, struct roots_view *view) {
 	}
 }
 
+/**
+ * Focus semantics of layer surfaces are somewhat detached from the normal focus
+ * flow. For layers above the shell layer, for example, you cannot unfocus them.
+ * You also cannot alt-tab between layer surfaces and shell surfaces.
+ */
+void roots_seat_set_focus_layer(struct roots_seat *seat,
+		struct wlr_layer_surface *layer) {
+	struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat->seat);
+	if (!layer) {
+		seat->focused_layer = NULL;
+		return;
+	}
+	if (seat->has_focus) {
+		struct roots_view *prev_focus = roots_seat_get_focus(seat);
+		wlr_seat_keyboard_clear_focus(seat->seat);
+		view_activate(prev_focus, false);
+	}
+	seat->has_focus = false;
+	if (layer->layer >= ZWLR_LAYER_SHELL_V1_LAYER_TOP) {
+		seat->focused_layer = layer;
+	}
+	if (keyboard != NULL) {
+		wlr_seat_keyboard_notify_enter(seat->seat, layer->surface,
+			keyboard->keycodes, keyboard->num_keycodes,
+			&keyboard->modifiers);
+	} else {
+		wlr_seat_keyboard_notify_enter(seat->seat, layer->surface,
+			NULL, 0, NULL);
+	}
+}
+
 void roots_seat_cycle_focus(struct roots_seat *seat) {
 	if (wl_list_empty(&seat->views)) {
 		return;