Re: [gtkmm] Q: how to centre in a VBox?

["D. R. Evans" <N7DR arrisi com>]

Martin Schulze wrote:

> Am 2003.10.22 18:01 schrieb(en) D. R. Evans:
>
> > I'm sure this is utterly trivial... but after several hours of trying, 
> > I'm giving up and asking for help.
> >
> > I have several HBoxes, which I would like to pack into a VBox that is 
> > displayed as a page in a Notebook.
> >
> > How do I pack things so that when the Notebook page displays, the 
> > HBoxes are vertically centred (either exactly or to a reasonable 
> > approximation) on the page? So that the page looks like:
> >
> > -------------------------------
> > |                             |
> > |                             |
> > |        hbox here            |
> > |        hbox here            |
> > |        hbox here            |
> > |                             |
> > |                             |
> > -------------------------------
>
>
> You could use a hbox and add e.g. an empty label before and
> after the widgets that should be shown centered with expand=true.

Yes, that's what I thought, too. But it doesn't actually work. I created a 
label with no contents and I got runtime errors...

... goes away for a few minutes and plays some more...

Ah! gtkmm seems to violate normal STL semantics regarding lifetimes. If I 
use an hbox that goes out of scope at the end of the page's constructor, 
then it doesn't work -- I have to include the hbox as an object carried 
inside the class that defines the page. Oddly, though, the same is not true 
for the label that goes inside the hbox -- that can go out of scope at the 
end of the constructor with no ill effects. Strange.

Anyway, I got it to work. Thanks very much. (I did actually try this idea 
out before posting, but since I was getting errors I figured that the basic 
idea must be wrong somehow, but your posting encouraged me that the basic 
idea was correct, but it was just the execution that was somehow flawed.)

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