I am using kchmviewer to read some documentations. 
I know that Okular can read them too. But the rendering of such documents by
Okular is not satisfactrory for me and because of it I need better tool.

This is the reason why I am using kchmviewer since years and was very happy
with it using it in all previous versions of openSUSE.

Unfortunately after moving to openSUSE Leap 42.1 I can not found any other
working option but must use Okular. This is because the kchmviewer from the
official release of openSUSE Leap 42.1 is useless, because can start but can
not open my chm files.

So I had to do some thing and try to remove it and install
kchmviewer-6.1-1.1.x86_64.rpm from the packages for openSUSE 13.2. It was
possible and Luckily I found that this package works just fine in my openSUSE
Leap 42.1.

This way my problem is solved for now but I believe the chmviewer version 7.2.1
from the openSUSE Leap 42.1 could be fixed to work as expected instead to be
useless.