Box shadow on transparent rectangle with border isn't rendered correctly

[tronical]

SlintPad link.

The following rectangle has a border but is otherwise transparent. The shadow cast from this should only contain he outline, not the transparent fill.

export component Demo {
    width: 300px;
    height: 300px;

    Rectangle {
       x: 10px;
       y: 10px;
       width: 150px;
       height: 150px;
       border-width: 10px;
       border-color: green;

       drop-shadow-blur: 5px;
       drop-shadow-offset-x: 10px;
       drop-shadow-offset-y: 10px;
       drop-shadow-color: red;
    }
}

[szecket]

this can be extended to any fill with transparency (or any border with transparency for that matter although I'm not sure you can render that on the box itself right now)
we could multiply the pixel in the shadow by the colour (including alpha) of the pixel in the casting object.
examples.
image png of line work casting shadow would right now be a rectangle
image of stain glass casting shadow...

[szecket]

if you're doing it by pixel then png would also work.