Great changes! Everything I hoped the new combinator would be for has been implemented. The only thing I would still like to see are the R/G check boxes on the Arythmetic combinator as well. This would make it possible, for example, to multiply each signal of the green cable with the corresponding s...

I guess it's a hardware fault. Please check if the key combination works on the following website: http://www.gigahype.com/nkey-rollover-test-page/
connecting an usb keyboard with an USB to PS/2 adapter might fix that issue.