Image alpha issues

I’m drawing an image to use as my background, but I want to make the image more transparent by setting the alpha to 0.5 or so.

It works fine, however, I have rotary sliders on top of the image, and soon after loading the backgrounds of the sliders go from transparent to white. The backgrounds are whatever I put in g.fillAll(), and I’m using background.multiplyAllAlphas(0.4) to change the background’s alpha.

Should I be doing this a different way?

Basically the backgrounds of the sliders are white and I want them transparent, but can’t seem to do that.

Fixed it: just changed opacity before drawing background instead.