QwtPlotOpenGLCanvas + Zooming, huge delays when Widget is fullscreen

[r2com]

Using the QwtPlotOpenGLCanvas now.
just addition of this line:

QwtPlotZoomer * zoomer = new QwtPlotZoomer( plotCanvas, true);

QwtPlotZoomer * zoomer = new QwtPlotZoomer( plotCanvas, true);

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Already gave me the needed minimum zooming capabilities.

One note though... unfortunately, lets say when I full-screen the whole app, and mark the zoom rectangle, there is a delay of about ~1s before the zoom occurs. Not sure why there is such huge delay? The plot only contains like 5-6 points...

Any ideas?