Comment 6 for bug 1857813

Can conform the issue since upgrading from QT 5.13 to 5.14.
MacOS 10.14.6 2.3.0-alpha-pre (build master r7055).

There was a svg viewport fix in 5.14 worth investigating
https://bugreports.qt.io/browse/QTBUG-70256

Another aspect of the bug is that stretching images inside mixxx do not work as they used to be.
As seen in OP´s video #1. The crossfader slider stretch is off, compared with QT 5.13.

Also, at least on macOS, there are major performance issues with this specific QT version.
On my machine, mixxx is at 100% CPU even while idle, just trying to render images.

It appears there have been some changes to the graphics stack .
https://wiki.qt.io/Qt_5.14_Release

As a stop-gap solution, i simplified the affected svg graphics for the Deere skin. There was some transformation going on (that rotates a shape around the point 0,0), also the unscaled handle graphics were bigger than the slider graphics. That was apparently not an issue until now.

At last, i added a maximum size for the crossfader slider image to stop the crossfader handle from overflowing the background graphic.

 As said, apparently there is an issue with mixxx internal STRETCH image function. The crossfader slider graphic ``slider-crossfader.svg`` does not stretch (expand) correct to the sliders widget size, but the ``slider-crossfader-AutoDJ.svg`` , active when using AUTODJ and defined in ``style.qss`` does.

Please test.