Tracking from one plot to another plot

[mqt]

I have two QWT plots. Both has same X axis but with different curves with different data. When I move my mouse in one plot, I was able to track the mouse location using Zoomer. When I move my mouse in first plot, I want a vertical line in second plot corresponding to the X Co-ordinate of mouse location in the first plot. What is the best way to achieve this? Probably I can use a marker, but how/when do I update its values? I searched for signals in plot, but could not found anything useful. Please help.

[Uwe]

A zoomer is for zooming, what you want to have is its baseclass: QwtPlotPicker. See the curvetracker example as inspiration.

For the first plot you probably want to have a picker without rubberband and a QwtPickerTrackerMachine.
For the second plot you could also use a picker, but in the end it might be easier to derive from QwtWidgetOverlay drawing a vertical line in drawOverlay().

Uwe

[mqt]

Uwe,
I was able to solve it by using QwtPlotPicker moved() signal. But for vertical line I have used a marker in second plot, who's value dynamically changed in a slot. This looks simple and serves the purpose.
One more thing I want to know. The moved() signal is emitted only when the mouse is dragged. Is there a way to emit signal for moving the mouse without dragging?
Similarly, for zoomer, it always uses click and click as box corners. I was able to change which mouse button to use but not able to make drag and drop locations as box corners.