Opacity and colour issue in Round Corners node

I am not sure if this is an issue at all but…

In the Round Corners node there is a colour select tool and an opacity slider. If I have a background colour with 0 opacity checked in the colour selector (and save as a PNG) I get a white background. If I then use the Opacity slider and set it to 0 then it does work

That’s by design because some color pickers don’t work well with the opacity slider in the color palette (and a lot of people don’t even notice it’s there).