Jitsi-jingle.jar - New plugin for voice call on Spark - Can't see buttons on window

Hi folks,

thanks for your work again ! I try to use jitsi-jingle.jar plugin 0.0.4 to make PC2PC call or voice chat.

I installed it on spark et remove all old plugin jingle in all folders, but when I try to call the second PC, I can hear the voice signal and see a small window on bottom right, but there is no buttons in the window so I can't respond to the call .....

Please help me :'(

Thanks.