I used message box as seperate dialog instead of sheets for mac OS, now i m working on it to spawn a sheet as message box instead of seperate one. I have tried setting the message box as a modal one: (messagebox.setWindowModality(QtCore.Qt.WindoModal)) and setting message box, parent dialog window flags as sheet (parentDialog.setWindowFlags(QtCore.Qt.Sheet) messagebox.setWindowFlags(QtCore.Qt.Sheet)) But the above commands are not working to create a sheet instead of seperate dialog. Does anyone have an idea of how to solve?