One widget has different view in Linux, Mac OS X, Windows

[Lucky_spirit]

Hi, everybody!
I write small application. I need to show some html page. To do it I use QTextBrowser. It showed this page good, but it's size was bigger than I need. I try to use QVBoxLayout and Stretch. It didn't bring a lot of advantage. Then I created my own class that was inherited by QTextBrowser and in new class I wrote my sizeHint() and minimumSizeHint() functions.
In Linux they show html page so as I want. With empty document size equals 0 and in other variants it widget becomes the necessary size. But it works only in Linux with KDE. In Windows and Mac OS X my widget became 0-sized in all cases. Can you help me?
Source code of my application is at GitHub here: "https://github.com/Lucky-spirit/Financial-analysis":https://github.com/Lucky-spirit/Financial-analysis . This widget is EvgTextBrowser.