Yes, there is a method for EditorControl to do that, but when readonly, it looks like the gray color overrides any background color that you set, so it only seems to work when the readonly option is turned off.
// works with the readonly option commented
w1 = Window(Object(‘Vert’ Object(‘Editor’ font: “Verdana” size: 16 /*readonly:true*/)))
w1.Vert.Editor.Set(“Hello”)
w1.Vert.Editor.SetBgndColor(RGB(50,50,255))