I have a qss with specified max-width: 

QToolTip { max-width: 300px; }

If the tooltip-text is short or consist of multiple short lines - it works fine. But once it get bigger, and occupy more lines, it does not extend the height of the tooltip properly.

To illustrate the problem, I will use Qt designer, as the issue easily reproducable there:

It is default tooltip-size (without restrictions).

Now, I will specify style-sheet for main-window: 

QToolTip { max-width: 200px; }

Actual result: As your can see, the height stays the same, the width decreased, so the text does not fit.

Expected result: The height of the tooltip is not limited - so it should be increased!

Suggested fix:

https://code.woboq.org/qt5/qtbase/src/widgets/widgets/qlabel.cpp.html#643

return (contentsSize + contentsMargin).expandedTo(q->minimumSize());

I think, here should be 

return (contentsSize + contentsMargin).expandedTo(q->minimumSize()).boundedTo(q->maximumSize());

But this suggestion might be mistaken because it is `QLabel` code, and it probably works fine probably fix should be in `QToolTip` code.