Probably has not a lot to do with your choice of bitcoin/bitcoin cash wallet... and a lot to do with keyloggers/malware etc... 
Whatever the cause, it is a good example of why people suggest moving BTC off of any private keys BEFORE attempting to claim the BCH or other fork coins from them... exposing your private key to an online environment puts coins at risk.
Whatever the cause, it is a good example of why people suggest moving BTC off of any private keys BEFORE attempting to claim the BCH or other fork coins from them... exposing your private key to an online environment puts coins at risk.
Do I understand correctly that in your opinion it was not the software that I used, but that someone monitored and copied my private key and initiated the stealing transaction outside from my computer? Would the details of the transfer on Blockchain help to diagnose what actually happened?