I realized there are a couple of errors in the code I posted. In the two case statements, if the mouse button press doesn't match the mouse pattern, then they get thrown away. This is wrong; the event should be passed up to the base class for it to handle instead. So, fix the code in both places by adding this:

Qt Code: 
  1. QwtPickerMachine::CommandList MyQwtPickerMachine::transition( const QwtEventPattern & eventPattern, const QEvent * pEvent )
  2. {
  3.     QwtPickerMachine::CommandList cmdList;
  4.  
  5.     switch( pEvent->type() )
  6.     {
  7.     case QEvent::MouseButtonPress:
  8.         {
  9.             if ( eventPattern.mouseMatch( QwtEventPattern::MouseSelect1, (const QMouseEvent *)pEvent )  )
  10.                {
  11. 		   //... same as original code
  12.                }
  13.                else  // These two lines are new; add the same thing to the double-click case
  14.                   cmdList	= QwtPickerClickPointMachine::transition( eventPattern, pEvent );
  15. 	}
  16. 	break;
  17.  
  18. 	default:
  19. 		cmdList	= QwtPickerClickPointMachine::transition( eventPattern, pEvent );
  20. 		break;
  21. 	}
  22. 	return cmdList;
  23. }
To copy to clipboard, switch view to plain text mode