modifier keys (among which windows key) unusable after focusing vmware

reason: caps lock appears in two places: lock and  control in xmodmap

lock        Caps_Lock (0x42)
control     Control_L (0x25),  Caps_Lock (0x42),  Control_R (0x69)

xmodmap becomes empty after giving focus to vmware if a key is doubled

solution:
setxkbmap
xmodmap -e "clear lock"

source:
https://askubuntu.com/questions/493404/ubuntu-14-04-vmware-6-left-ctrl-and-right-shift-not-functioning