my polygons flicker

I am developping a kind of oscilloscope interface to monitor real time values.

To draw the traces I use polygons that I refresh with a PtTimer widget with a 20ms callback. Unfortunatly I got a flickering effects depending of the video monitor refresh rate. This is not surprising and this beating effect between close frequencies is well known.

Is there any way to synchronize the polygon refresh with the monitor vertical sync ?

Thanks for help

If you are using QNX6, try putting the widget into a PtOsContainer. This will render into off-screen and the blit it in one big slam. Very fast/smooth drawing, but a little more CPU overhead.