Axis not aligning with Spectrogram image

[Ronayn]

Hello,

I cant get the axis to align properly to the plot (see attached image). I'd like the ticks to be centered on the data bins -- not on the left side of the data bin. I've tried aligning the canvas to the axis, changing margins, and adjusting the axis -- all with no luck.

I am using Qwt5.2.0 on FC6. I can also post the code, if that would help -- but it was take almost verbatim from the spectrogram example code.