Not sure what would be the most appropriate node. Im doing a drag and drop item that will need an icon, text and some numbers inside it. Maybe a TextureRect, ColorRect, or Panel.
I used a StyleBoxFlat
styleBoxFlat.BorderColor = new Color(1,1,0,1);
styleBoxFlat.SetBorderWidthAll(10);
testNode.AddThemeStyleboxOverride("normal", styleBoxFlat);
As I said, this works on Buttons, but not on the other nodes I tried. Im curious why that is.