Hey, my first bug fix. Two displaying objects were overlapping creating
a unwanted effect.

Karl Ramberg

'From Squeak2.8alpha of 19 February 2000 [latest update: #2005] on 22
April 2000 at 4:29:57 pm'!

!WarpBlt class methodsFor: 'examples' stamp: 'kfr 4/22/2000 16:26'!
test12   "Display restoreAfter: [WarpBlt test12]"
 "Just like test1, but comparing smooth to non-smooth warps"
 | warp pts r1 p0 p ext warp2 |
 Utilities informUser: 'Choose a rectangle with interesting stuff'
  during: [r1 _ Rectangle originFromUser: 50 at 50.
    Sensor waitNoButton].
 Utilities informUser: 'Now click down and up
and move the mouse around the dot'
  during: [p0 _ Sensor waitClickButton.
    (Form dotOfSize: 8) displayAt: p0].
 warp _ (self toForm: Display)
  cellSize: 2;  "installs a colormap"
  clipRect: (0 at 0 extent: r1 extent*5);
  sourceForm: Display;
  combinationRule: Form over.
 warp2 _ (self toForm: Display)
  clipRect: ((0 at 0 extent: r1 extent*5) translateBy: 250 at 0);
  sourceForm: Display;
  combinationRule: Form over.
 [Sensor anyButtonPressed] whileFalse:
  [p _ Sensor cursorPoint.
  pts _ {r1 topLeft. r1 bottomLeft. r1 bottomRight. r1 topRight}
   collect: [:pt | pt rotateBy: (p-p0) theta about: r1 center].
  ext _ (r1 extent*((p-p0) r / 20.0 max: 0.1)) asIntegerPoint.
  warp copyQuad: pts toRect: (r1 extent*5-ext//2 extent: ext).
  warp2 copyQuad: pts toRect: ((r1 extent*5-ext//2 extent: ext)
translateBy: 250 at 0).
  ]! !