why on Linux ,doesn't work?

[maider]

Good afternoon!

I'm having a problem on Linux. My computer has got Windows Xp system. I have done an application where I use a transparent button which has a white border and text.
I have done in this way:
background-color: rgba(255, 255, 255, 0);
color: rgb(255, 255, 255);

Nowadays, i want to do the same but on Linux. To achieve my goal, I have inserted a virtual machine into windows and there install qt.
The problem is that when i run the application the border of the button doesn't appreciate. It looks as if it is a transparent button without border.

Do you know why? what am i doing wrong?

thanks!!