Qt Designer crashes when set a negative value in border-image

border-style: solid;
border-width: 2px;
border-radius: 32px;
border-color: transparent;
border-image: url(...) -10 0 0 -10; /* top right bottom left */

When i set a negative value in the first or last number of border-image Qt Designer crashes.

Also, the image is not being 'resized' correctly with negative values, and its causing glitches:

With image and negative values it 'zoom' the image correctly: