docs: public Bitmap getDrawingBitmap() {
          /*
           * Layer manager only starts drawing a new bitmap when the last one is swapped (taken to
           * the screen). This ensures that the layer manager draws not too many frames. (only as
           * much as can get displayed).
           */
          synchronized (this.allowSwap) {
              this.allowSwap.waitDisabled();
              Bitmap b = this.lmBitmap.lock();
              if (b != null) {
                  b.setBackgroundColor(this.displayModel.getBackgroundColor());
              }
              return b;
          }
      }