The QWidgetAction are not always visible

[hizoka]

Hi,

for my software, I would like use the QWidgetAction class for my menubar.

I like it !

!http://hizo.fr/img/qt/menu01.png!

But with other Desktop like gnome / unity, the QWidgetAction are not visible :

!http://hizo.fr/img/qt/menu02.png!

Why this bug ?
I have missed a package, a dependancy ?

Thank you and sorry for my english.

Kubuntu 14.10 64bits – Qt 4.8.6