XDG-Shell: how to change window size?

I added xdg-shell v5 to app to draw windows. When I send set_fullscreen or set_maximize commands, I see correctly set window states and correct sizes in configure event but nothing is happens.

My configure event function:

    static void
xdg_surface_handle_configure(void *data,
              struct xdg_surface *xdg_surface,
              int32_t width,
              int32_t height,
              struct wl_array *states,
              uint32_t serial) {
    printf("Configure event got, width: %d, height: %d\n", width, height);
    VirtIOGPU *g = (VirtIOGPU*) data;

    g->window_state.activated = g->window_state.fullscreen =
    g->window_state.maximized = g->window_state.resizing = false;

    uint32_t *state;
    wl_array_for_each(state, states) {
        if(*state == XDG_SURFACE_STATE_MAXIMIZED) {
            printf("Surface state: XDG_SURFACE_STATE_MAXIMIZED\n");
            g->window_state.maximized = true;
        } else if(*state == XDG_SURFACE_STATE_FULLSCREEN) {
            printf("Surface state: XDG_SURFACE_STATE_FULLSCREEN\n");
            g->window_state.fullscreen = true;
        } else if(*state == XDG_SURFACE_STATE_RESIZING) {
            printf("Surface state: XDG_SURFACE_STATE_RESIZING\n");
            g->window_state.resizing = true;
        } else if(*state == XDG_SURFACE_STATE_ACTIVATED) {
            printf("Surface state: XDG_SURFACE_STATE_ACTIVATED\n");
            g->window_state.activated = true;
        }
    }

    if (width > 0 && height > 0) {
        g->prev_width = g->width;
        g->prev_height = g->height;
        g->width = width;
        g->height = height;
    } else {
        g->width = g->prev_width;
        g->height = g->prev_height;
    }

    xdg_surface_ack_configure(xdg_surface, serial);

    wl_surface_damage(g->surface, 0, 0, g->width, g->height);
    wl_surface_commit(g->surface);
    wl_display_dispatch_pending(g->display);
    wl_display_flush(g->display);
}

So, how to see maximized window after I sent set_maximized? Is it possible to unminimize minimized window programmatically (now by Super+Tab)?

Your client probably needs to attach and commit a new buffer with the correct dimensions to the surface. The compositor has done everything it's supposed to do, and expects your client to resize.