Nested activation boxes in Rational Modeler?

Question

Is it possible to create nested activation boxes in Rational Modeler 7.5? It always seems to want to merge the boxes together into one.

My use case is an object method that calls another method on the same object. I'd like to show a nested activation box for the second call, superimposed on top of the first.

Here's an example (in mine, message2 would loop back onto sender):

Answer 1

The activation bar has been erased from the sequence diagram OMG UML 2 specification. It means that this element is only a graphical element which has no equivalent to the UML model. The activation bar has therefore been erased from RSA 7.5

I think this activation bar elimination is a mistake. Omondo EclipseUML has refused to erased the activation bar into UML 2.3 so if you need this graphical element then feel free to try this tool.