QuickControls 2 TextField and TextArea background styling problem when disabled

I wanted to style QuickControls 2 TextFields for an application of mine. Like described here, for this the background item should be changed.

But the problem here is, that when the item is disabled, the item gets grayed out not by the background but by some other way. Although greying out is Ok as default behaviour, i can't change that by replacing the background Rectangle (and I also didn't find any other way). For Buttons and other controls it is possible to define how the look even if they are disabled, but TextFields and TextAreas are greyed out no matter what i do with the background.

So if i want my TextfField with a solid border when disabled for example, i can't do it. Because even if i set the border.color of the Rectangle to solid "#000" it will not be black but grey.

The attached example shows the difference of Items with "same styling applied" for enabled and disabled TextFields, TextAreas and Buttons. As you clearly can see, the TextFields and TextAreas are still looking different when disabled while the Buttons look the same, like it should be by my opinion.