PyQt4

This is regarding the precision in "QDoubleSpinBox". With out sub classing things were not working as I expected.
Qt Code: 
  1. class QxDoubleSpinBox(QtGui.QDoubleSpinBox):
  2.     def __init__(self, parent=None, value=0.):
  3.         QtGui.QDoubleSpinBox.__init__(self, parent)
  4.         self.setRange(0., 1.)
  5.         self.setValue(0.421)
  6.         self.setSingleStep(0.001)
  7.         self.setFixedWidth(70)
  8.         self.setWrapping(True)
  9.         self.setDecimals(3)
  10.  
  11.     def valueFromText(self, str):
  12.         return FixedPoint(str, 3)
  13.  
  14.     def textFromValue(self, value):
  15.         print "textFromValue = ", value
  16.         return str(value)
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As soon as I start the application, here are the results printed:
Qt Code: 
  1. textFromValue =  0.42
  2. textFromValue =  0.42
  3. textFromValue =  0.42
  4. textFromValue =  0.0
  5. textFromValue =  1.0
  6. textFromValue =  0.42
  7. textFromValue =  0.42
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I have no idea what's going on here and why "textFromValue" is getting called so many times with values getting changed each time. I was hoping that sub classing will solve the problem of precision.

How do I solve this?