memory maintence in gtk

[Todd Gureckis <gureckis well com>]

When you create a dialog window to say, set preference for a application,
is it necessary/customary to free all the memory allocated by the creation
of the window once it is closed... for example running free() on all
the GtkWidget pointers in the dialog window?

Is there a built in way to do this in gtk?  This is a kind of un-informed
observation, but when i create a dialog, then later gtk_widget_destroy()
the dialog, the memory size of my application does not shrink when I list
it in top.  I wasn't sure if it would be better to save the memory,
and dynamically allocate the whole dialog window, or leave it in memory,
so cpu is saved the next time the dialog window is created.

any suggestion/answers would be appreciated,

tod.