At Thu, 23 Feb 2017 10:09:59 +0000, Erich Rast wrote:
> I have an editor-canvas A subclasses inside a vertical-panel subclass B
> and below A there is another vertical-panel subclass C in B. C is shown
> or hidden by removing and adding it via change-children in B. 
> However, even though A has stretchable-height set to #t, it does not
> resize to fill the whole area of B automatically when the C is removed.
> (C itself is not stretchable-height.)
> I tried refresh but it didn't have any visible effect and on-size does
> nothing by default. Is there a way to programmatically trigger the same
> size calculation and display adjustment as when the panels/canvases are
> created? Or do I have to do this manually?

Does the editor canvas in the example below stretch when the button
removes its parent vertical panel? (If not, you're seeing a bug...)

If so, is there a change that makes it behave like your program?


#lang racket/gui

(define f (new frame% [label "Stretch"]))

(define B (new vertical-panel%
               [parent f]))

(define A (new editor-canvas%
               [parent B]))

(define C (new vertical-panel%
               [parent B]))

 (new button%
      [parent C]
      [label "Remove Me"]
      [callback (lambda (c e)
                  (send B change-children (lambda (l) (list A))))]))

(send f show #t)

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