roundedBoxRgba method
Implementation
int roundedBoxRgba(
math.Rectangle<double> rect, int rad, int r, int g, int b, int a) {
// 241
return gfx.roundedBoxRgba(this, rect.left.toInt(), rect.top.toInt(),
rect.right.toInt(), rect.bottom.toInt(), rad, r, g, b, a);
}