Qt5 on Windows 7 Arial font: Thai is very small

Question

I am attempting to port our desktop application from Qt 4.8.4 to Qt 5.2.1. On Windows, I've found that Thai text displayed with Arial is much smaller in a QPlainTextEdit than it was under Qt4. In fact, it is too small to read.

I load the Thai file into our application running under Qt4, and it is fine. On the same Windows 7 x64 machine, I load the file into my Qt5 version of our application, and the text is illegibly small.

Incidentally, normal English text using the same font and the same QPlainTextEdit is the same legible size for both the Qt4 and Qt5 versions of our application.

Is this a bug in Qt5? Or maybe there's something tricky about porting to Qt5 involving QFont or QPlainTextEdit?

Answer 1

See this bug report. This is fixed in Qt 5.4.0.