message: Make clip rect apply to fewer calls
  The clip rect is mainly useful for drawing list items, and accounting
  for the scroll position, where items may be clipped by the bounds of the
  scroll area.
diff: @@ -244,11 +244,10 @@ void ListBox::update()
  const auto borderColor = hasFocus() ? mBorderColorActive : mBorderColorNormal;
  renderer.drawBox(mRect, borderColor);
  + renderer.drawBoxFilled(mScrollArea, mBackgroundColorNormal);
  renderer.clipRect(mRect);
  - renderer.drawBoxFilled(mScrollArea, mBackgroundColorNormal);
  -
  // Highlight currently selected item
  auto itemBounds = mScrollArea;
  itemBounds.height = static_cast<int>(mLineHeight);
  @@ -274,9 +273,9 @@ void ListBox::update()
  textPosition.y += mLineHeight;
  }
  - mSlider.update();
  -
  renderer.clipRectClear();
  +
  + mSlider.update();
  }
  