changing font size in examples\richtext\calendar can lock-up or crash a phone

I have been investigating memory leaks in Qt by running apps and looking at the amount of memory still allocated at app exit time. One test was with examples\richtext\calendar on Symbian MCL wk27. I was starting the app, clicking the font size up/down arrows to take it down to 1, then up. The number of heap cells allocated at app exit varied with the number of different sizes used. It did not change if a font size was used more than once, so I guess there's a cache there. But when I took the font size a lot higher, two times the phone rebooted and another it froze. The font sizes were 32, 50 and 63 for the probelms I've seen so far.