Widgets from IupControls library error, e.g: could not import iupMatrix

[UrKr]

When trying to use widgets from the IupControls library, I get "could not import" runtime error. Do I need a dll?

import iup
let m = iup.matrix(nil)

[radebrecht]

same error here. IUP doc tells me to call IupControlsOpen, which produces: could not import: IupControlsOpen
After having a look at the code it seems that the matrix lives in IupControls but is referenced as an element in iup. see here and here