CAD11 — "Cadsystem" interface issue

The interface "Cadsystem" provides access on a "CadUserInterface" by the
method

boolean is_interactive(out CadUserInterface gui);

Normally loading a model in the CAD engine and showing it with the editor
are two different tasks.
"create_model" and "open_model" obvioulsy are related to CAD-Engine
activity. GUI activities like showing, hiding etc. are not mandatory
implicated. If methods like "create_model" and "open_model" are intended not
to include GUI operation then functionality to control the
"CadUserInterface" is missing.
Therefore the following function would be very helpful (They assume that a
model is already loaded by the CAD engine):

createWindow(model) // Creates a window and put it in the foreground
hideWindow(model) // hides an existing window but doesn't
delete it
foregroundWindow(model) // put an existing (even if hided) window in the
foreground
deleteWindow(model) // delete the window and the corresponding window
data structure but NOT the model within the CAD engine

Every model should throw a "ModelNotLoadedException" if the model is not
loaded.

Summing up this should allow for a separated control of activities within
the CAD-engine and the editor.

see above