In some CHM files, font increasing/decreasing doesn't work as expected: Just the "title" of the page changes it's size. (For a sample file get an Apress book in CHM)
Using KCHMViewer 5.1
Qt version 4.6.2
Same here. It's sad that nobody comments on this.
Kchmviewer 5.1 on Ubuntu Maverick 10.10.
xchm can show different font size for the same file.