Morph>>layoutBounds: and Morph>>doLayoutIn: share the job of 
repositioning/sizing a morph, but only the latter invalidates changed 
areas. Sample below:

showLayoutProblem
"
Morph showLayoutProblem
"
     | paneHeight row searchCount |

     row  _ AlignmentMorph newRow.
     row addMorph: (StringMorph contents: 'hello').

     searchCount _ StringMorph new contents: '?'.
     row addMorphBack: (
         AlignmentMorph newColumn
             layoutInset: 5;
             color: Color tan;
             listCentering: #center;
             hResizing: #shrinkWrap;
             addMorph: searchCount;
             yourself
     ).

     paneHeight _ StringMorph new contents: '?'.
     row addMorphBack: (
         AlignmentMorph newColumn
             layoutInset: 5;
             color: Color gray;
             listCentering: #center;
             hResizing: #shrinkWrap;
             addMorph: paneHeight;
             yourself
     ).

     searchCount contents: 'ssss'.
     paneHeight contents: 'pppp'.
     Morph new
         extent: 300 at 100;
         color: Color white;
         addMorph: row;
         openInWorld.
     [
         (Delay forSeconds: 3) wait.
         paneHeight contents: 'p'.
     ] fork.

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