This is very common problem and till yet unresolved. The Elantech driver disables right button + left button touchpad click. In the result you cannot aim and shoot in games also you cannot code that kind of interaction in your applications.

Driver detects LMB+RMB click but it somehow filters it.

I could not find correct entry in the registry to disable that obviously horrible setting.

Please notice:

1. I have the latest drivers the problem existed with really old ones, a year old, on Windows 7, 8 and 8.1 ones and current.

2. It has nothing to do with the Windows or hardware but only with the Elantech driver settings.

3. Driver detects LMB+RMB click -> it is shown on a dynamic icon on a task bar also uninstalling drivers fix the problem, but then you can't use your touchpad fully.