pyqt5 Getting started with pyqt5 Showing a tooltip

Example

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):
        
        QToolTip.setFont(QFont('SansSerif', 10))
        
        self.setToolTip('This is a <b>QWidget</b> widget')
        
        btn = QPushButton('Button', self)
        btn.setToolTip('This is a <b>QPushButton</b> widget')
        btn.resize(btn.sizeHint())
        btn.move(50, 50)       
        
        self.setGeometry(300, 300, 300, 200)
        self.setWindowTitle('Tooltips')    
        self.show()
        
        
if __name__ == '__main__':
    
    app = QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

Analysis

QToolTip.setFont(QFont('SansSerif', 10))

This static method sets a font used to render tooltips. We use a 10px SansSerif font.

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

To create a tooltip, we call the setTooltip() method. We can use rich text formatting.

btn = QPushButton('Button', self)
btn.setToolTip('This is a <b>QPushButton</b> widget')

We create a push button widget and set a tooltip for it.

btn.resize(btn.sizeHint())
btn.move(50, 50) 

The button is being resized and moved on the window. The sizeHint() method gives a recommended size for the button.