message: Draw Slider buttons as calculated Rectangle
  The width and height are set equal, so the two are equivalent. It makes
  more sense to use both width and height though.
diff: @@ -348,8 +348,8 @@ void Slider::draw()
  if (mSliderType == SliderType::SLIDER_VERTICAL)
  {
  renderer.drawImageRect(mSlideBar.x(), mSlideBar.y(), mSlideBar.width(), mSlideBar.height(), mSkinMiddle);// slide area
  - renderer.drawImageRect(mButton1.x(), mButton1.y(), mButton1.height(), mButton1.height(), mSkinButton1);// top button
  - renderer.drawImageRect(mButton2.x(), mButton2.y(), mButton2.height(), mButton2.height(), mSkinButton2);// bottom button
  + renderer.drawImageRect(mButton1.x(), mButton1.y(), mButton1.width(), mButton1.height(), mSkinButton1);// top button
  + renderer.drawImageRect(mButton2.x(), mButton2.y(), mButton2.width(), mButton2.height(), mSkinButton2);// bottom button
  //renderer.drawImageRect(mButtonUp.x(), mButtonUp.y(), mButtonUp.height(), mButtonUp.height(), mSkinButtonLeft);// top button
  // Slider
  @@ -372,8 +372,8 @@ void Slider::draw()
  else
  {
  renderer.drawImageRect(mSlideBar.x(), mSlideBar.y(), mSlideBar.width(), mSlideBar.height(), mSkinMiddle); // slide area
  - renderer.drawImageRect(mButton1.x(), mButton1.y(), mButton1.height(), mButton1.height(), mSkinButton1); // left button
  - renderer.drawImageRect(mButton2.x(), mButton2.y(), mButton2.height(), mButton2.height(), mSkinButton2); // right button
  + renderer.drawImageRect(mButton1.x(), mButton1.y(), mButton1.width(), mButton1.height(), mSkinButton1); // left button
  + renderer.drawImageRect(mButton2.x(), mButton2.y(), mButton2.width(), mButton2.height(), mSkinButton2); // right button
  // Slider
  mSlider.height(mSlideBar.height()); // height = slide bar height
  