import sys

from PyQt5.QtWidgets import (QWidget, QToolTip,

    QPushButton, QApplication)

from PyQt5.QtGui import QFont    

class Example(QWidget):

    def __init__(self):

        super().__init__()

        self.initUI()

    def initUI(self):

        #Window设置

        self.setGeometry(300, 300, 300, 200)

        self.setWindowTitle('Tooltip提示信息')

        self.setToolTip('This is a <b>Window</b>')

        self.setFont(QFont('consolas',10)) #设置整个Window内字体

        # Button设置

        btn = QPushButton('Button', self)

        btn.move(50, 50)

        btn.resize(50,30)

        #btn.setFont(QFont('simsun',12)) #仅设置Button的字体

        btn.setToolTip('This is a <b>Button</b>')

        self.show() 

if __name__ == '__main__':

    app = QApplication(sys.argv)

    ex = Example()

    sys.exit(app.exec_())