Fix X11 clients getting stuck minimized

Usually it should be enough to simply not grant a client's
minimize request, however some applications (Steam, fullscreen
games in Wine) don't wait for the compositor and minimize anyway,
getting them stuck in an unrecoverable state.
Restoring them immediately lead to heavy flickering when unfocused
on my test application (Earth Defense Force 5 via Steam), so it's
preferable to grant their request without actually minimizing and
then restoring them once they are in focus again.

include/sway/tree/view.h

@@ -147,6 +147,7 @@ struct sway_xwayland_view {
 	struct wl_listener request_move;
 	struct wl_listener request_resize;
 	struct wl_listener request_maximize;
+	struct wl_listener request_minimize;
 	struct wl_listener request_configure;
 	struct wl_listener request_fullscreen;
 	struct wl_listener request_activate;

sway/desktop/xwayland.c

@@ -508,6 +508,26 @@ static void handle_request_fullscreen(struct wl_listener *listener, void *data)
 	transaction_commit_dirty();
 }
 
+static void handle_request_minimize(struct wl_listener *listener, void *data) {
+	struct sway_xwayland_view *xwayland_view =
+		wl_container_of(listener, xwayland_view, request_minimize);
+	struct sway_view *view = &xwayland_view->view;
+	struct wlr_xwayland_surface *xsurface = view->wlr_xwayland_surface;
+	if (!xsurface->mapped) {
+		return;
+	}
+
+	struct wlr_xwayland_minimize_event *e = data;
+	struct sway_seat *seat = input_manager_current_seat();
+	bool focused =
+			seat->wlr_seat->keyboard_state.focused_surface == xsurface->surface;
+	if (!focused && e->minimize) {
+		wlr_xwayland_surface_set_minimized(xsurface, true);
+	} else {
+		wlr_xwayland_surface_set_minimized(xsurface, false);
+	}
+}
+
 static void handle_request_move(struct wl_listener *listener, void *data) {
 	struct sway_xwayland_view *xwayland_view =
 		wl_container_of(listener, xwayland_view, request_move);
@@ -653,6 +673,10 @@ void handle_xwayland_surface(struct wl_listener *listener, void *data) {
 		&xwayland_view->request_fullscreen);
 	xwayland_view->request_fullscreen.notify = handle_request_fullscreen;
 
+	wl_signal_add(&xsurface->events.request_minimize,
+		&xwayland_view->request_minimize);
+	xwayland_view->request_minimize.notify = handle_request_minimize;
+
 	wl_signal_add(&xsurface->events.request_activate,
 		&xwayland_view->request_activate);
 	xwayland_view->request_activate.notify = handle_request_activate;

sway/input/seat.c

@@ -1197,6 +1197,15 @@ void seat_set_focus(struct sway_seat *seat, struct sway_node *node) {
 		// the workspace needs to be arranged
 		arrange_workspace(new_workspace);
 	}
+
+	#if HAVE_XWAYLAND
+	// Some X11 clients minimize without waiting for the compositor to allow it
+	if (container && container->view && container->view->type == SWAY_VIEW_XWAYLAND
+			&& container->view->wlr_xwayland_surface->minimized) {
+		wlr_xwayland_surface_set_minimized(
+			container->view->wlr_xwayland_surface, false);
+	}
+	#endif
 }
 
 void seat_set_focus_container(struct sway_seat *seat,