[Trac #1249] Calculator cannot input negative numbers

[Zarro Boogs per Child]

#1249: Calculator cannot input negative numbers
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 Reporter:  bert                 |       Owner:  maurotorres
     Type:  defect               |      Status:  new        
 Priority:  normal               |   Milestone:  Untriaged  
Component:  calculator-activity  |    Keywords:             
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 Press "1", "(-)", "1", get -9.

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Ticket URL: <http://dev.laptop.org/ticket/1249>
One Laptop Per Child <http://laptop.org/>