How to get the x an y corrdinates from mouse postion

[Uwe]

With picker->setDisplayMode(QwtPicker::AlwaysOn) the positions is always displayed.

If you want to see that the QwtPlotPicker::moved() signal is emitted - even when the mouse is not pressed - there are many different ways to do it. Probably the most easiest one is to overload QwtPlotPicker::widgetMouseMoveEvent this way:

YourPicker::widgetMouseMoveEvent(QMouseEvent *me)
{
   QwtPlotPicker::widgetMouseMoveEvent(me);
   emit moved(invTransform(me->pos));
}

YourPicker::widgetMouseMoveEvent(QMouseEvent *me)
{
   QwtPlotPicker::widgetMouseMoveEvent(me);
   emit moved(invTransform(me->pos));
}

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HTH,
Uwe