QwtPlot in QSplitter

Hello. I have QSplitter and QFrame, containing only one QwtPlot in it. While I'm dragging QSplitter border, QwtPlot area shrinks smoothly, but reaches some size and collapses.

I want to get shrinking till the end. How can I reach it?

Thanks.

QwtPlot:

Code:

---

setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
	setMinimumSize(0,0);
	setBaseSize(0,0);
	canvas()->setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Preferred);
	canvas()->setMinimumSize(0,0);
	canvas()->setBaseSize(0,0);

---

Seems like QwtScaleWidget's minimum width width was the greatest among QwtPlot's child widgets. At least setting scale interval to (0,0) solved the problem