static struct viewport clip_rect;
static bool clipped = false;

static void rb_clip(void *handle, int x, int y, int w, int h)
{
    LOGF("rb_clip(%d %d %d %d)", x, y, w, h);
    clip_rect.x = x;
    clip_rect.y = y;
    clip_rect.width  = w;
    clip_rect.height = h;
    clip_rect.font = FONT_UI;
    clip_rect.drawmode = DRMODE_SOLID;
#if LCD_DEPTH > 1
    clip_rect.fg_pattern = LCD_DEFAULT_FG;
    clip_rect.bg_pattern = LCD_DEFAULT_BG;
#endif
    rb->lcd_set_viewport(NULL);
    rb->lcd_set_viewport(&clip_rect);
    clipped = true;
}

static void rb_unclip(void *handle)
{
    LOGF("rb_unclip");
    rb->lcd_set_viewport(NULL);
    clipped = false;
}