This is an 3rd party patch that never worked properly.
Here ( http://sourceforge.net/p/qwt/code/HE...-6.1-multiaxes ) you find a branch with an official implementation for multi axes. It is almost complete ( QwtPlot::sizeHint() and QwtPlotRescaler are not yet finished ) and is planned to be merged into the main line with Qwt 6.3 ( too many API changes for Qwt 6.2 ). This branch is actively maintained ( gets all bug fixes and new stuff of trunk ) and you can send bug reports.
Uwe
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