Width of tab header - QTabWidget

Hi, I've got another problem with my web browser. I've got a class ExtraTab which inherits from QTabWidget. Every tab works properly, but the width of "tab header" is variable and depends on length of website title which is displayed there. I need to make width of this element constant. I've tried to set it using setMaximumSize(int w, int h), but that function influenced the whole area of ExtraTab stylesheet. To leave no doubt, I'm attaching a picture wih marked the element which I want to set its width:
http://i43.tinypic.com/al67bs.jpg
Please help me to deal with it.
Greetings.