Please _don't_. IMO the context menu should not select objects
because the user defines the context (maybe there should be a 
menu for nothing selected. Context := Diagram).

If the context menu would select something it should definitely
check if there already was something selected. And it _must_
not change it, because the user always should know better ... 

Mass reassign of bugs to dia-maint@bugzilla.gnome.org.

I agree with Hans on this.  Several context menus use the mouse point to place new corners and such.  Mixing this with selecting other objects would be confusing.  Allowing a select when there's nothing selecting would lead to a confusing inconsistency in the behaviour.

Usually, pointing and clicking with the mouse selects something.
The contextual menu is *contextual*. It depends of the context, and
the context is set by pointing and clicking.
I user would expect that, when he ask for the contextual menu, the 
context be consitent with what is under the mouse. That is why clicking
with the button the raise contextual menu should set the context 
(= selection) the same way.

Oh and yes, there should be a context for nothing selected. This way
the context is the whole diagram.

Maybe I should have gone into more detail the first time.
Often selcting objects isn't a simple task. (That's why
there are so many options in the Select menu :-)
If a user has finished such a task it would be _highly_
annoying if some smart programmer would say 'Hey I don't
care, you just right clicked not within the current 
selcetion. I create a new one.'
Please try it yourself with a complex diagram.
BTW: The _left_ mouse button is used to select something.
Neither the middle nor the right one. Dia behaves consistently
with any other program I know (Try rigth-clicking in your
favourite word processor, browser, drawing program, ...)

Setting to NOTABUG.

agreed