Steps:
1. Create a new .qml file and open it in designer mode.
2. Add a "Rectangle" control to the canvas.
3. Try to set the color to this "rectangle" and its border.
4. Try to set the "A" value of the color property.

Expected Result:
The color of the rectangle in designer changes according the "a" value. change to editor mode, the color string should be in "ARGB" mode include the "a" value have set.

Actually Result:
If you set the "a" value to "0" for rectangle color, the color actually turned to "#000000". other values have no effective on the color.
each value of "a" takes no effective on border.color.
Change to editor mode to see the code. No "A" value include in the color string.

Please refer to the attached pictures.