fix focustop(): prefer a visible fullscreen client

Problem (reproducible on vanilla 0.9, unrelated to any local patch):
1. fullscreen client A on tag 3 (MOD+e);
2. MOD+0 to view all tags;
3. MOD+1 to switch to tag 1, focus lands on client B;
4. MOD+0 again: client A is displayed fullscreen, covering everything,
   but the focused client is the invisible B;
5. so MOD+e / MOD+q act on B behind A and the user thinks MOD+e does
   not work on A until A is clicked with the mouse.

Root cause: focustop() returns the first VISIBLEON() client on the
fstack, but VISIBLEON() only checks whether the client is on a
currently visible tag; it does not check whether the client is covered
by a fullscreen client. When switching back to tag 0, the last focused
client B is first on the fstack, so B gets the focus while A is still
displayed fullscreen.

Fix: focustop() first looks for a visible fullscreen client on the
fstack (at most one fullscreen client per monitor is actually shown,
and it always sits on top, covering the whole monitor), and only falls
back to the previous "first visible client" if there is none. As a
result:
- after a tag switch the focus goes back to the fullscreen client that
  actually occupies the screen, so MOD+e / MOD+q behave as expected;
- the fullscreen_bg decision in arrange() is fixed as a side effect
  (it used to be turned off when the focus was not on the fullscreen
  client, so a non-opaque fullscreen surface could reveal other
  clients behind it, which violates the protocol);
- focusstack() already returns early when the focused client is
  fullscreen, so MOD+j/k and the arrow keys no longer move the focus
  to a covered client either.

Verified with headless dwl, two foot clients and keys injected through
zwp_virtual_keyboard_v1: before the fix the last step gives
focal = winB / fullscreen 0; after the fix focal = winA / fullscreen 1,
and MOD+e then restores A as expected.

ta: 20261031_022753

README.md

@@ -153,6 +153,7 @@ given the base on which it is built. Implemented default features are:
 - Support screen lockers via ext-session-lock-v1 protocol
 - Various Wayland protocols
 - XWayland support as provided by wlroots (can be enabled in `config.mk`)
+- Zero flickering - Wayland users naturally expect that "every frame is perfect"
 - Layer shell popups (used by Waybar)
 - Damage tracking provided by scenegraph API
 

client.h

@@ -324,19 +324,36 @@ client_set_scale(struct wlr_surface *s, float scale)
 	wlr_surface_set_preferred_buffer_scale(s, (int32_t)ceilf(scale));
 }
 
-static inline void
+/* Returns nonzero if the client has to commit a buffer with the new size */
+static inline uint32_t
 client_set_size(Client *c, uint32_t width, uint32_t height)
 {
 #ifdef XWAYLAND
 	if (client_is_x11(c)) {
 		wlr_xwayland_surface_configure(c->surface.xwayland,
 				c->geom.x + c->bw, c->geom.y + c->bw, width, height);
-		return;
+		return (int)width != client_surface(c)->current.width
+				|| (int)height != client_surface(c)->current.height;
 	}
 #endif
-	if ((int32_t)width != c->surface.xdg->toplevel->current.width
-			|| (int32_t)height != c->surface.xdg->toplevel->current.height)
-		wlr_xdg_toplevel_set_size(c->surface.xdg->toplevel, (int32_t)width, (int32_t)height);
+	if ((int32_t)width == c->surface.xdg->toplevel->scheduled.width
+			&& (int32_t)height == c->surface.xdg->toplevel->scheduled.height)
+		return 0;
+	return wlr_xdg_toplevel_set_size(c->surface.xdg->toplevel, (int32_t)width, (int32_t)height);
+}
+
+static inline void
+client_send_frame_done_iterator(struct wlr_surface *s, int sx, int sy, void *data)
+{
+	wlr_surface_send_frame_done(s, data);
+}
+
+static inline void
+client_send_frame_done(Client *c)
+{
+	struct timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+	wlr_surface_for_each_surface(client_surface(c), client_send_frame_done_iterator, &now);
 }
 
 static inline void

config.def.h

@@ -12,7 +12,6 @@ static const float rootcolor[]             = COLOR(0x222222ff);
 static const float bordercolor[]           = COLOR(0x444444ff);
 static const float focuscolor[]            = COLOR(0x005577ff);
 static const float urgentcolor[]           = COLOR(0xff0000ff);
-/* This conforms to the xdg-protocol. Set the alpha to zero to restore the old behavior */
 static const float fullscreen_bg[]         = {0.0f, 0.0f, 0.0f, 1.0f}; /* You can also use glsl colors */
 
 /* tagging - TAGCOUNT must be no greater than 31 */

dwl.c

@@ -126,6 +126,9 @@ typedef struct {
 	struct wl_list flink;
 	struct wlr_box geom; /* layout-relative, includes border */
 	struct wlr_box prev; /* layout-relative, includes border */
+	struct wlr_box current; /* geom currently shown in the scene graph */
+	struct wlr_scene_node *snapshot; /* content shown while resizing */
+	uint32_t resize_serial; /* nonzero while waiting for a resized buffer */
 	struct wlr_box bounds; /* only width and height are used */
 	union {
 		struct wlr_xdg_surface *xdg;
@@ -262,6 +265,7 @@ typedef struct {
 
 /* function declarations */
 static void applybounds(Client *c, struct wlr_box *bbox);
+static void applygeom(Client *c);
 static void applyrules(Client *c);
 static void arrange(Monitor *m);
 static void arrangelayer(Monitor *m, struct wl_list *list,
@@ -324,6 +328,7 @@ static void mapnotify(struct wl_listener *listener, void *data);
 static void maximizenotify(struct wl_listener *listener, void *data);
 static void monocle(Monitor *m);
 static void motionabsolute(struct wl_listener *listener, void *data);
+static char **monoff(struct wlr_output *wlr_output);
 static void motionnotify(uint32_t time, struct wlr_input_device *device, double sx,
 		double sy, double sx_unaccel, double sy_unaccel);
 static void motionrelative(struct wl_listener *listener, void *data);
@@ -349,9 +354,12 @@ static void setfullscreen(Client *c, int fullscreen);
 static void setlayout(const Arg *arg);
 static void setmfact(const Arg *arg);
 static void setmon(Client *c, Monitor *m, uint32_t newtags);
+static void setmonoff(struct wlr_output *wlr_output, int off);
 static void setpsel(struct wl_listener *listener, void *data);
 static void setsel(struct wl_listener *listener, void *data);
 static void setup(void);
+static struct wlr_scene_node *snapshot(struct wlr_scene_node *node,
+		struct wlr_scene_tree *parent, void *data);
 static void spawn(const Arg *arg);
 static void startdrag(struct wl_listener *listener, void *data);
 static void tag(const Arg *arg);
@@ -361,6 +369,11 @@ static void togglefloating(const Arg *arg);
 static void togglefullscreen(const Arg *arg);
 static void toggletag(const Arg *arg);
 static void toggleview(const Arg *arg);
+static void transactionapply(void);
+static void transactioncheck(void *data);
+static void transactioncommit(Client *c, int ready);
+static void transactionschedule(void);
+static int transactiontimeout(void *data);
 static void unlocksession(struct wl_listener *listener, void *data);
 static void unmaplayersurfacenotify(struct wl_listener *listener, void *data);
 static void unmapnotify(struct wl_listener *listener, void *data);
@@ -432,6 +445,15 @@ static struct wl_list mons;
 static Monitor *selmon;
 static int consumed[KEY_MAX + 1];
 
+/* Transactions: the scene graph is updated only once all visible clients have
+ * committed buffers with their new size, or after TRANSACTION_TIMEOUT ms */
+#define TRANSACTION_TIMEOUT 100
+static struct wl_event_source *transaction_idle;
+static struct wl_event_source *transaction_timer;
+static int transaction_waiting;
+static struct wl_array ghosts; /* struct wlr_scene_node *, unmapped clients */
+static struct wl_array offmons; /* char *, names of outputs turned off by clients */
+
 /* global event handlers */
 static struct wl_listener cursor_axis = {.notify = axisnotify};
 static struct wl_listener cursor_button = {.notify = buttonpress};
@@ -460,12 +482,14 @@ static struct wl_listener request_set_sel = {.notify = setsel};
 static struct wl_listener request_set_cursor_shape = {.notify = setcursorshape};
 static struct wl_listener request_start_drag = {.notify = requeststartdrag};
 static struct wl_listener start_drag = {.notify = startdrag};
+static struct wl_listener drag_icon_destroy = {.notify = destroydragicon};
 static struct wl_listener new_session_lock = {.notify = locksession};
 static struct wl_listener new_foreign_toplevel_capture_request = {.notify = capturerequest};
 
 #ifdef XWAYLAND
 static void activatex11(struct wl_listener *listener, void *data);
 static void associatex11(struct wl_listener *listener, void *data);
+static void commitx11(struct wl_listener *listener, void *data);
 static void configurex11(struct wl_listener *listener, void *data);
 static void createnotifyx11(struct wl_listener *listener, void *data);
 static void dissociatex11(struct wl_listener *listener, void *data);
@@ -516,6 +540,41 @@ applybounds(Client *c, struct wlr_box *bbox)
 		c->geom.y = bbox->y;
 }
 
+void
+applygeom(Client *c)
+{
+	struct wlr_box clip;
+	Client *p = client_get_parent(c);
+
+	/* We move all floating clients to LyrTile while in floating layout
+	 * to avoid "real" floating clients be always on top */
+	wlr_scene_node_reparent(&c->scene->node, layers[c->isfullscreen
+			|| (p && p->isfullscreen) ? LyrFS
+			: c->isfloating && c->mon->lt[c->mon->sellt]->arrange ? LyrFloat
+			: LyrTile]);
+
+	c->current = c->geom;
+	if (c->snapshot) {
+		wlr_scene_node_destroy(c->snapshot);
+		c->snapshot = NULL;
+		wlr_scene_node_set_enabled(&c->scene_surface->node, 1);
+	}
+
+	/* Update scene-graph, including borders */
+	wlr_scene_node_set_position(&c->scene->node, c->geom.x, c->geom.y);
+	wlr_scene_node_set_position(&c->scene_surface->node, c->bw, c->bw);
+	wlr_scene_rect_set_size(c->border[0], c->geom.width, c->bw);
+	wlr_scene_rect_set_size(c->border[1], c->geom.width, c->bw);
+	wlr_scene_rect_set_size(c->border[2], c->bw, c->geom.height - 2 * c->bw);
+	wlr_scene_rect_set_size(c->border[3], c->bw, c->geom.height - 2 * c->bw);
+	wlr_scene_node_set_position(&c->border[1]->node, 0, c->geom.height - c->bw);
+	wlr_scene_node_set_position(&c->border[2]->node, 0, c->bw);
+	wlr_scene_node_set_position(&c->border[3]->node, c->geom.width - c->bw, c->bw);
+
+	client_get_clip(c, &clip);
+	wlr_scene_subsurface_tree_set_clip(&c->scene_surface->node, &clip);
+}
+
 void
 applyrules(Client *c)
 {
@@ -555,37 +614,18 @@ arrange(Monitor *m)
 		return;
 
 	wl_list_for_each(c, &clients, link) {
-		if (c->mon == m) {
-			wlr_scene_node_set_enabled(&c->scene->node, VISIBLEON(c, m));
+		if (c->mon == m)
 			client_set_suspended(c, !VISIBLEON(c, m)
 					&& (!c->image_capture_source
 					|| wl_list_empty(&c->image_capture_source->resources)));
-		}
 	}
 
-	wlr_scene_node_set_enabled(&m->fullscreen_bg->node,
-			(c = focustop(m)) && c->isfullscreen);
-
 	strncpy(m->ltsymbol, m->lt[m->sellt]->symbol, LENGTH(m->ltsymbol));
 
-	/* We move all clients (except fullscreen and unmanaged) to LyrTile while
-	 * in floating layout to avoid "real" floating clients be always on top */
-	wl_list_for_each(c, &clients, link) {
-		if (c->mon != m || c->scene->node.parent == layers[LyrFS])
-			continue;
-
-		wlr_scene_node_reparent(&c->scene->node,
-				(!m->lt[m->sellt]->arrange && c->isfloating)
-						? layers[LyrTile]
-						: (m->lt[m->sellt]->arrange && c->isfloating)
-								? layers[LyrFloat]
-								: c->scene->node.parent);
-	}
-
 	if (m->lt[m->sellt]->arrange)
 		m->lt[m->sellt]->arrange(m);
-	motionnotify(0, NULL, 0, 0, 0, 0);
-	checkidleinhibitor(NULL);
+
+	transactionschedule();
 }
 
 void
@@ -788,6 +828,8 @@ checkidleinhibitor(struct wlr_surface *exclude)
 void
 cleanup(void)
 {
+	char **name;
+
 	cleanuplisteners();
 #ifdef XWAYLAND
 	wlr_xwayland_destroy(xwayland);
@@ -809,6 +851,14 @@ cleanup(void)
 	 * Destroy it until it's fixed on the wlroots side */
 	wlr_backend_destroy(backend);
 
+	if (transaction_idle)
+		wl_event_source_remove(transaction_idle);
+	wl_event_source_remove(transaction_timer);
+	wl_array_release(&ghosts);
+	wl_array_for_each(name, &offmons)
+		free(*name);
+	wl_array_release(&offmons);
+
 	wl_display_destroy(dpy);
 	/* Destroy after the wayland display (when the monitors are already destroyed)
 	   to avoid destroying them with an invalid scene output. */
@@ -990,6 +1040,8 @@ commitnotify(struct wl_listener *listener, void *data)
 		return;
 	}
 
+	transactioncommit(c, c->resize_serial && c->surface.xdg->current.configure_serial
+			>= c->resize_serial);
 	resize(c, c->geom, (c->isfloating && !c->isfullscreen));
 }
 
@@ -1186,14 +1238,17 @@ createmon(struct wl_listener *listener, void *data)
 	 * monitor supports only a specific set of modes. We just pick the
 	 * monitor's preferred mode; a more sophisticated compositor would let
 	 * the user configure it. */
-	wlr_output_state_set_mode(&state, wlr_output_preferred_mode(wlr_output));
-
 	/* Set up event listeners */
 	LISTEN(&wlr_output->events.frame, &m->frame, rendermon);
 	LISTEN(&wlr_output->events.destroy, &m->destroy, cleanupmon);
 	LISTEN(&wlr_output->events.request_state, &m->request_state, requestmonstate);
 
-	wlr_output_state_set_enabled(&state, 1);
+	/* Some monitors disconnect when they are turned off and reconnect shortly
+	 * after, so keep outputs that were turned off disabled. */
+	if (!monoff(wlr_output)) {
+		wlr_output_state_set_mode(&state, wlr_output_preferred_mode(wlr_output));
+		wlr_output_state_set_enabled(&state, 1);
+	}
 	wlr_output_commit_state(wlr_output, &state);
 	wlr_output_state_finish(&state);
 
@@ -1219,6 +1274,12 @@ createmon(struct wl_listener *listener, void *data)
 	 * output (such as DPI, scale factor, manufacturer, etc).
 	 */
 	m->scene_output = wlr_scene_output_create(scene, wlr_output);
+
+	if (!wlr_output->enabled) {
+		updatemons(NULL, NULL);
+		return;
+	}
+
 	if (m->m.x == -1 && m->m.y == -1)
 		wlr_output_layout_add_auto(output_layout, wlr_output);
 	else
@@ -1363,7 +1424,6 @@ destroydragicon(struct wl_listener *listener, void *data)
 	focusclient(focustop(selmon), NULL, 1);
 	motionnotify(0, NULL, 0, 0, 0, 0);
 	wl_list_remove(&listener->link);
-	free(listener);
 }
 
 void
@@ -1550,7 +1610,6 @@ focusclient(Client *c, LayerSurface *l, int lift)
 		/* Don't change border color if there is an exclusive focus or we are
 		 * handling a drag operation */
 		if (!(old_l && old_l->layer_surface->current.keyboard_interactive == ZWLR_LAYER_SURFACE_V1_KEYBOARD_INTERACTIVITY_EXCLUSIVE)
-				&& !(old_c && client_wants_focus(old_c))
 				&& !seat->drag)
 			client_set_border_color(c, focuscolor);
 	}
@@ -1641,10 +1700,14 @@ Client *
 focustop(Monitor *m)
 {
 	Client *c;
-	wl_list_for_each(c, &fstack, flink) {
+
+	wl_list_for_each(c, &fstack, flink)
+		if (VISIBLEON(c, m) && c->isfullscreen)
+			return c;
+
+	wl_list_for_each(c, &fstack, flink)
 		if (VISIBLEON(c, m))
 			return c;
-	}
 	return NULL;
 }
 
@@ -2019,6 +2082,17 @@ motionabsolute(struct wl_listener *listener, void *data)
 	motionnotify(event->time_msec, &event->pointer->base, dx, dy, dx, dy);
 }
 
+char **
+monoff(struct wlr_output *wlr_output)
+{
+	char **name;
+	wl_array_for_each(name, &offmons) {
+		if (!strcmp(*name, wlr_output->name))
+			return name;
+	}
+	return NULL;
+}
+
 void
 motionnotify(uint32_t time, struct wlr_input_device *device, double dx, double dy,
 		double dx_unaccel, double dy_unaccel)
@@ -2205,6 +2279,7 @@ outputmgrapplyortest(struct wlr_output_configuration_v1 *config, int test)
 		/* Ensure displays previously disabled by wlr-output-power-management-v1
 		 * are properly handled*/
 		m->asleep = 0;
+		setmonoff(wlr_output, !config_head->state.enabled);
 
 		/* Don't move monitors if position wouldn't change. This avoids
 		 * wlroots marking the output as manually configured.
@@ -2323,6 +2398,10 @@ powermgrsetmode(struct wl_listener *listener, void *data)
 
 	m->gamma_lut_changed = 1; /* Reapply gamma LUT when re-enabling the output */
 	wlr_output_state_set_enabled(&state, event->mode);
+	/* The output was reconnected while off and was never modeset */
+	if (event->mode && !m->wlr_output->current_mode)
+		wlr_output_state_set_mode(&state, wlr_output_preferred_mode(m->wlr_output));
+	setmonoff(m->wlr_output, !event->mode);
 	wlr_output_commit_state(m->wlr_output, &state);
 
 	m->asleep = !event->mode;
@@ -2385,7 +2464,7 @@ void
 resize(Client *c, struct wlr_box geo, int interact)
 {
 	struct wlr_box *bbox;
-	struct wlr_box clip;
+	uint32_t serial;
 
 	if (!c->mon || !client_surface(c)->mapped)
 		return;
@@ -2396,20 +2475,27 @@ resize(Client *c, struct wlr_box geo, int interact)
 	c->geom = geo;
 	applybounds(c, bbox);
 
-	/* Update scene-graph, including borders */
-	wlr_scene_node_set_position(&c->scene->node, c->geom.x, c->geom.y);
-	wlr_scene_node_set_position(&c->scene_surface->node, c->bw, c->bw);
-	wlr_scene_rect_set_size(c->border[0], c->geom.width, c->bw);
-	wlr_scene_rect_set_size(c->border[1], c->geom.width, c->bw);
-	wlr_scene_rect_set_size(c->border[2], c->bw, c->geom.height - 2 * c->bw);
-	wlr_scene_rect_set_size(c->border[3], c->bw, c->geom.height - 2 * c->bw);
-	wlr_scene_node_set_position(&c->border[1]->node, 0, c->geom.height - c->bw);
-	wlr_scene_node_set_position(&c->border[2]->node, 0, c->bw);
-	wlr_scene_node_set_position(&c->border[3]->node, c->geom.width - c->bw, c->bw);
+	if ((serial = client_set_size(c, c->geom.width - 2 * c->bw,
+			c->geom.height - 2 * c->bw)))
+		c->resize_serial = serial;
 
-	client_set_size(c, c->geom.width - 2 * c->bw, c->geom.height - 2 * c->bw);
-	client_get_clip(c, &clip);
-	wlr_scene_subsurface_tree_set_clip(&c->scene_surface->node, &clip);
+	if (interact || (!c->resize_serial && wlr_box_equal(&c->geom, &c->current))) {
+		c->resize_serial = 0;
+		applygeom(c);
+		return;
+	}
+
+	/* Until the transaction is applied, keep showing the current content
+	 * instead of buffers with the new size at the old position. */
+	if (c->resize_serial) {
+		if (!c->snapshot && c->scene->node.enabled
+				&& (c->snapshot = snapshot(&c->scene_surface->node, c->scene, c)))
+			wlr_scene_node_set_enabled(&c->scene_surface->node, 0);
+		/* The scene graph doesn't send frame done events to hidden
+		 * surfaces, but the client may be waiting for one to redraw */
+		client_send_frame_done(c);
+	}
+	transactionschedule();
 }
 
 void
@@ -2510,14 +2596,10 @@ setcursorshape(struct wl_listener *listener, void *data)
 void
 setfloating(Client *c, int floating)
 {
-	Client *p = client_get_parent(c);
 	c->isfloating = floating;
 	/* If in floating layout do not change the client's layer */
 	if (!c->mon || !client_surface(c)->mapped || !c->mon->lt[c->mon->sellt]->arrange)
 		return;
-	wlr_scene_node_reparent(&c->scene->node, layers[c->isfullscreen ||
-			(p && p->isfullscreen) ? LyrFS
-			: c->isfloating ? LyrFloat : LyrTile]);
 	arrange(c->mon);
 	printstatus();
 }
@@ -2530,8 +2612,6 @@ setfullscreen(Client *c, int fullscreen)
 		return;
 	c->bw = fullscreen ? 0 : borderpx;
 	client_set_fullscreen(c, fullscreen);
-	wlr_scene_node_reparent(&c->scene->node, layers[c->isfullscreen
-			? LyrFS : c->isfloating ? LyrFloat : LyrTile]);
 
 	if (fullscreen) {
 		c->prev = c->geom;
@@ -2597,6 +2677,22 @@ setmon(Client *c, Monitor *m, uint32_t newtags)
 	focusclient(focustop(selmon), NULL, 1);
 }
 
+void
+setmonoff(struct wlr_output *wlr_output, int off)
+{
+	char **name = monoff(wlr_output), **last;
+
+	if (off && !name && (name = wl_array_add(&offmons, sizeof(*name)))) {
+		if (!(*name = strdup(wlr_output->name)))
+			offmons.size -= sizeof(*name);
+	} else if (!off && name) {
+		free(*name);
+		last = (char **)((char *)offmons.data + offmons.size) - 1;
+		*name = *last;
+		offmons.size -= sizeof(*name);
+	}
+}
+
 void
 setpsel(struct wl_listener *listener, void *data)
 {
@@ -2735,6 +2831,10 @@ setup(void)
 	wl_list_init(&clients);
 	wl_list_init(&fstack);
 
+	transaction_timer = wl_event_loop_add_timer(event_loop, transactiontimeout, NULL);
+	wl_array_init(&ghosts);
+	wl_array_init(&offmons);
+
 	xdg_shell = wlr_xdg_shell_create(dpy, 6);
 	wl_signal_add(&xdg_shell->events.new_toplevel, &new_xdg_toplevel);
 	wl_signal_add(&xdg_shell->events.new_popup, &new_xdg_popup);
@@ -2856,6 +2956,57 @@ setup(void)
 #endif
 }
 
+struct wlr_scene_node *
+snapshot(struct wlr_scene_node *node, struct wlr_scene_tree *parent, void *data)
+{
+	/* Copy the visible part of a scene graph subtree, keeping references to
+	 * the buffers so that they can be shown after the client changes them */
+	struct wlr_scene_node *child, *copy;
+	struct wlr_scene_tree *tree;
+	struct wlr_scene_rect *rect;
+	struct wlr_scene_buffer *src, *buffer;
+
+	if (!node->enabled)
+		return NULL;
+
+	switch (node->type) {
+	case WLR_SCENE_NODE_TREE:
+		tree = wlr_scene_tree_create(parent);
+		wl_list_for_each(child, &wlr_scene_tree_from_node(node)->children, link)
+			snapshot(child, tree, data);
+		copy = &tree->node;
+		break;
+	case WLR_SCENE_NODE_RECT:
+		rect = wlr_scene_rect_from_node(node);
+		copy = &wlr_scene_rect_create(parent, rect->width, rect->height, rect->color)->node;
+		break;
+	case WLR_SCENE_NODE_BUFFER:
+		src = wlr_scene_buffer_from_node(node);
+		buffer = wlr_scene_buffer_create(parent, NULL);
+		wlr_scene_buffer_set_dest_size(buffer, src->dst_width, src->dst_height);
+		wlr_scene_buffer_set_opaque_region(buffer, &src->opaque_region);
+		wlr_scene_buffer_set_opacity(buffer, src->opacity);
+		wlr_scene_buffer_set_filter_mode(buffer, src->filter_mode);
+		wlr_scene_buffer_set_transfer_function(buffer, src->transfer_function);
+		wlr_scene_buffer_set_primaries(buffer, src->primaries);
+		wlr_scene_buffer_set_color_encoding(buffer, src->color_encoding);
+		wlr_scene_buffer_set_color_range(buffer, src->color_range);
+		wlr_scene_buffer_set_source_box(buffer, &src->src_box);
+		wlr_scene_buffer_set_transform(buffer, src->transform);
+		wlr_scene_buffer_set_buffer(buffer, src->buffer);
+		copy = &buffer->node;
+		break;
+	default:
+		return NULL;
+	}
+
+	copy->data = data;
+	wlr_scene_node_set_position(copy, node->x, node->y);
+	if (node->parent == parent)
+		wlr_scene_node_place_above(copy, node);
+	return copy;
+}
+
 void
 spawn(const Arg *arg)
 {
@@ -2875,7 +3026,7 @@ startdrag(struct wl_listener *listener, void *data)
 		return;
 
 	drag->icon->data = &wlr_scene_drag_icon_create(drag_icon, drag->icon)->node;
-	LISTEN_STATIC(&drag->icon->events.destroy, destroydragicon);
+	wl_signal_add(&drag->icon->events.destroy, &drag_icon_destroy);
 }
 
 void
@@ -2977,6 +3128,88 @@ toggleview(const Arg *arg)
 	printstatus();
 }
 
+void
+transactionapply(void)
+{
+	struct wlr_scene_node **ghost;
+	Client *c;
+	Monitor *m;
+
+	wl_event_source_timer_update(transaction_timer, 0);
+	transaction_waiting = 0;
+
+	wl_array_for_each(ghost, &ghosts)
+		wlr_scene_node_destroy(*ghost);
+	ghosts.size = 0;
+
+	wl_list_for_each(c, &clients, link) {
+		c->resize_serial = 0;
+		if (!c->mon)
+			continue;
+		if (c->mon->wlr_output->enabled)
+			wlr_scene_node_set_enabled(&c->scene->node, VISIBLEON(c, c->mon));
+		applygeom(c);
+	}
+
+	wl_list_for_each(m, &mons, link) {
+		if (m->wlr_output->enabled)
+			wlr_scene_node_set_enabled(&m->fullscreen_bg->node,
+					(c = focustop(m)) && c->isfullscreen);
+	}
+
+	motionnotify(0, NULL, 0, 0, 0, 0);
+	checkidleinhibitor(NULL);
+}
+
+void
+transactioncheck(void *data)
+{
+	Client *c;
+
+	transaction_idle = NULL;
+
+	/* Hidden clients don't have to redraw before the layout is shown */
+	wl_list_for_each(c, &clients, link) {
+		if (c->resize_serial && VISIBLEON(c, c->mon) && c->mon->wlr_output->enabled) {
+			if (!transaction_waiting) {
+				/* Don't restart the timer on updates of the pending
+				 * layout, so the delay is bounded */
+				wl_event_source_timer_update(transaction_timer, TRANSACTION_TIMEOUT);
+				transaction_waiting = 1;
+			}
+			return;
+		}
+	}
+
+	transactionapply();
+}
+
+void
+transactioncommit(Client *c, int ready)
+{
+	if (c->resize_serial && ready) {
+		c->resize_serial = 0;
+		transactionschedule();
+	} else if (c->snapshot) {
+		/* This buffer is not shown, let the client draw again */
+		client_send_frame_done(c);
+	}
+}
+
+void
+transactionschedule(void)
+{
+	if (!transaction_idle)
+		transaction_idle = wl_event_loop_add_idle(event_loop, transactioncheck, NULL);
+}
+
+int
+transactiontimeout(void *data)
+{
+	transactionapply();
+	return 0;
+}
+
 void
 unlocksession(struct wl_listener *listener, void *data)
 {
@@ -3003,6 +3236,7 @@ unmapnotify(struct wl_listener *listener, void *data)
 {
 	/* Called when the surface is unmapped, and should no longer be shown. */
 	Client *c = wl_container_of(listener, c, unmap);
+	struct wlr_scene_node *ghost, **slot;
 	if (c == grabc) {
 		cursor_mode = CurNormal;
 		grabc = NULL;
@@ -3011,6 +3245,15 @@ unmapnotify(struct wl_listener *listener, void *data)
 		focused_client = NULL;
 
 	if (!client_is_unmanaged(c)) {
+		/* Keep showing the client until the transaction rearranging the
+		 * remaining ones is applied, to not show a gap */
+		if ((ghost = snapshot(&c->scene->node, c->scene->node.parent, NULL))) {
+			if ((slot = wl_array_add(&ghosts, sizeof(ghost))))
+				*slot = ghost;
+			else
+				wlr_scene_node_destroy(ghost);
+			transactionschedule();
+		}
 		wl_list_remove(&c->link);
 		setmon(c, NULL, 0);
 		wl_list_remove(&c->flink);
@@ -3034,6 +3277,9 @@ unmapnotify(struct wl_listener *listener, void *data)
 	c->image_capture_source = NULL;
 	wlr_scene_node_destroy(&c->scene->node);
 	client_surface(c)->data = NULL;
+	c->snapshot = NULL;
+	c->resize_serial = 0;
+	c->current = (struct wlr_box){0};
 	printstatus();
 	motionnotify(0, NULL, 0, 0, 0, 0);
 }
@@ -3233,20 +3479,26 @@ xytonode(double x, double y, struct wlr_surface **psurface,
 		Client **pc, LayerSurface **pl, double *nx, double *ny)
 {
 	struct wlr_scene_node *node;
+	struct wlr_scene_surface *scene_surface;
 	struct wlr_surface *surface = NULL;
+	Client *c = NULL;
 	int layer;
 
-	for (layer = NUM_LAYERS - 1; !surface && layer >= (locked ? LyrBlock : 0); layer--) {
+	for (layer = NUM_LAYERS - 1; !surface && !c && layer >= (locked ? LyrBlock : 0); layer--) {
 		if (layer == LyrIMPopup ||
-				!(node = wlr_scene_node_at(&layers[layer]->node, x, y, nx, ny)))
+				!(node = wlr_scene_node_at(&layers[layer]->node, x, y, nx, ny))
+				|| node->type != WLR_SCENE_NODE_BUFFER)
 			continue;
 
-		if (node->type == WLR_SCENE_NODE_BUFFER)
-			surface = wlr_scene_surface_try_from_buffer(
-					wlr_scene_buffer_from_node(node))->surface;
+		if ((scene_surface = wlr_scene_surface_try_from_buffer(
+				wlr_scene_buffer_from_node(node))))
+			surface = scene_surface->surface;
+		else /* snapshot of a client during a transaction */
+			c = node->data;
 	}
 
 	if (psurface) *psurface = surface;
+	if (pc) *pc = c;
 	toplevel_from_wlr_surface(surface, pc, pl);
 }
 
@@ -3299,10 +3551,21 @@ associatex11(struct wl_listener *listener, void *data)
 {
 	Client *c = wl_container_of(listener, c, associate);
 
+	LISTEN(&client_surface(c)->events.commit, &c->commit, commitx11);
 	LISTEN(&client_surface(c)->events.map, &c->map, mapnotify);
 	LISTEN(&client_surface(c)->events.unmap, &c->unmap, unmapnotify);
 }
 
+void
+commitx11(struct wl_listener *listener, void *data)
+{
+	Client *c = wl_container_of(listener, c, commit);
+	struct wlr_surface *surface = client_surface(c);
+
+	transactioncommit(c, surface->current.width == c->geom.width - 2 * (int)c->bw
+			&& surface->current.height == c->geom.height - 2 * (int)c->bw);
+}
+
 void
 configurex11(struct wl_listener *listener, void *data)
 {
@@ -3351,6 +3614,7 @@ void
 dissociatex11(struct wl_listener *listener, void *data)
 {
 	Client *c = wl_container_of(listener, c, dissociate);
+	wl_list_remove(&c->commit.link);
 	wl_list_remove(&c->map.link);
 	wl_list_remove(&c->unmap.link);
 }