title: PyQt4: set size of QGridLayout depending on size of QMainWindow
body: <p>I'm writing a little Qt application with Python. I've created QMainWindow, which have a QGridLayout. In each grid I'm adding QTextBrowser Widget. I want left side of my grid to be not bigger than 25% of window. So I'll have two QTextBrowsers: one is 25% of window's width, and another is 75% of window's width. How can I do it? Thanks!</p>