LightDM, Resize Onboard

Hi, I'm using a Debian Testing based Distro with LightDM as Display Manager and XFCE as the Desktop. I have installed and configured OnBoard to start and run at the login display automatically by editing the /etc/lightdm/lightdm-gtk-greeter.conf file and adding the following line:

"keyboard = onboard --theme=DarkRoom --layout=Compact --keep-aspect --size=1000x600"

The theme and layout settings work fine, but the size never changes, the key for moving and resizing are missing. I can't do any dragging to resize the keyboard.

On my system I can work the keyboard, but if you are using a tablet with a different resolution, the OnBoard keyboard might be too small, and the keys difficult to use if you happen to have large fingers.

I have also looked at /etc/onboard/onboard-defaults.conf file, but any changes I do there don't seem to do make any difference when in LightDM.

Once logged in to the XFCE Desktop, there is no problem resizing the OnBoard Keyboard. There it works via terminal commands and by dragging it's corners. It is just within LightDM where nothing happens.

Does anyone have a solution for this?

Thanks for your help,
rindi1