That would be good to be able to create a sequence diagram for multiple operations (at least in the same class, but for
multiple would be also needed).

Imagine I have a public method that is traversing some collection and for each object do a private operation, which is
not complex, but should be shown on the main diagram as well.

By selecting multiple operations I would select this public and this specific private method, and generator would know,
that he must 'go into' the selected method and also create a diagram part.

Maybe the uml generator would need to know from which operation to start whole generating, but that may be done in some
small wizard.