Proper code

[gib]

I'm sure you are right, d_stranz. Since this is the Qwt forum, I'm hoping that some Qwt guru can point out my error. As far as I can determine I am using QwtPlot in the essentially same way that I do in several other programs, but obviously something is different. The other programs all use the same procedure, in code much more complex than my test code. In those programs I select the plots to display from a list of candidates, and maintain an array of pointers to Plot objects, where the Plot object is as specified in the attachment. In my test code I am trying to use QwtPlot directly. I did try working with the Plot object, but with no better success.