It would make your text go away, because QLabel can't display a QwtText.

Look at the simple example and play with the curve titles. If you find a title, where you think, that the layout calculation is wrong tell us about it and post a screenshot.

Uwe

PS: Some basic infos ( OS, Qt/Qwt versions, which font, rich- or plain Text, which curve title ...) would be more helpful than posting speculations.