I'm using Ubuntu 14.04 lts and sikulix 1.1.0.

while running sikulix script in the ordinary way it's working great, but when i'm trying to use Xvfb [just like suggested here](https://stackoverflow.com/questions/26032706/how-to-get-sikuli-working-in-headless-mode), it's says that there is no wmctrl installed. and thats not true, this is the output in shell:

```
running SikuliX: -Xmx512M -Dfile.encoding=UTF-8 -Dsikuli.FromCommandLine
-jar ./sikulix.jar -r ../sikuliscripts/script.sikuli
[info] runcmd: lsb_release -i -r -s 
[error] RunTimeIDE:  *** terminating: command 'wmctrl' is not executable
please check the Availability!

```

thanks in advance!