How to set a graphics effect to a tree widget and its contents

[mrvk]

I would like to blur my mainwindow whenever a model dialog is shown on top of that. Using QGraphicsBlurEffect, I am able to set the background (mainwindow) to the desired effect. But if there is a tree widget in the main window, then the tree widget contents are not getting blurred.
How can I achieve that ?

Thanks for any help