Is it possible to use a deque as plot data?

[Uwe]

Edit: I discovered a serious problem with the QwtSeriesData API. It takes ownership of the data...

No you have discovered a problem in your class derived from QwtSeriesData.

QwtSeriesData is just an interface - completely unrelated to how the application stores or shares its samples. In fact it is even possible to calculate samples on the fly storing nothing - like in QwtSyntheticPointData.

Uwe