🚀 go-pugleaf

Hi,
	I'm a neophyte to InterViews and GUI design, and hope someone
can shed some light on the way InterViews 3.0 does geometry managemenet.
This is the model I've come up with:

   To request canvas area, a primitive glyph fills out a Requisition 
   from within its constructor.  A composite glyph fills out a Requisition
   from within Glyph::request by combining the Requisitions of its
   children.  

If a glyph wants to change its canvas area during an application, does
it rewrite its Requisition from within Glyph::request?  Are the
functions request, allocate, draw event-triggered?  What causes them to
be called?

In the ScaleToFit example in the ref. manual, the body of ScaleToFit is
a Image with fixed stretchability/shrinkability.  I guess ScaleToFit
inherits this Requisition.  If I added a row of buttons on top, separated
from the ScaleToFit glyph by vglue, and then resize the window, how does
InterViews figure out how much canvas area to allocate to the ScaleToFit
glyph, & how much to allocate to the row of buttons and vglue?  Will
window resize cause allocate and draw to be called for every glyph?

help is most appreciated,
louie