Names once were stdmulti.widget[1-4]. Now they are .widget[0-3].
I'll fix this so that the names are stdmulti.widget[0-3] as it seems to be intended by the code I found. However, this is a major incompatibility to previous versions, in particular code that used stdmulti.widget4 to address the 3d window. Most uses of stdmulti.widget[1-2] is interchangeable like "give me a 2d render window, I don't care which one", which is probably why this wasn't discovered earlier.
Color preferences for render windows should work again after the fix. Preferences are incompatible to old preference files, though.