How to halt only if shift is pressed?

in Pharo I'd 开发者_运维技巧like Object>>halt to halt only if shift is pressed, so that I don't break down my image. How do I do that?

So, for example, I'd like to be able to add a self halt. into Array>>add:, without losing my image.

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Object>>haltifShiftPressed
 Sensor leftShiftDown ifTrue: [self halt].

Cool, this Textbox can Syntax-Highlight Smalltalk-code

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self haltIf: [Sensor shiftPressed]

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I'll do the following now, Merging Oscar's and Richard's solution:

Object>>h
  self haltIf: [Sensor shiftPressed]