Make widget borders colored on activation in Pyside2

Question

I have a group of three QRadioButtons and three QGroupBoxes on my Pyside2 window application. When I click one radio button - a group box gets enabled.

if self.ui.radioButton_1.isChecked():
    self.ui.groupBox_1.setEnabled(True)
    self.ui.groupBox_2.setEnabled(False)
    self.ui.groupBox_3.setEnabled(False)    
elif self.ui.radioButton_2.isChecked():
    self.ui.groupBox_1.setEnabled(False)
    self.ui.groupBox_2.setEnabled(True)
    self.ui.groupBox_3.setEnabled(False)    
elif self.ui.radioButton_3.isChecked():
    self.ui.groupBox_1.setEnabled(False)
    self.ui.groupBox_2.setEnabled(False)
    self.ui.groupBox_3.setEnabled(True)

Is it possible via implementing styles or enabling some option in Qt Designer to make borders of a chosen QGroupBox colored on activation? Something like this:

The exact width of green lines in not important, the colored border lightening matters only.

Answer 1

You can set a border in the style sheet for QGroupBox with the :enabled pseudo-state.

import sys
from PySide2.QtWidgets import *

class Template(QWidget):

    def __init__(self):
        super().__init__()
        grid = QGridLayout(self)
        for i in range(3):
            radio_btn = QRadioButton(f'RadioButton_{i + 1}', checked=not i)
            group_box = QGroupBox(f'GroupBox_{i + 1}', enabled=not i)
            radio_btn.toggled[bool].connect(group_box.setEnabled)
            hbox = QHBoxLayout(group_box)
            hbox.addWidget(QLabel(f'Test_{i + 1}'))
            hbox.addWidget(QLineEdit())
            grid.addWidget(radio_btn, i, 0)
            grid.addWidget(group_box, i, 1)

        self.setStyleSheet('''
        QGroupBox {
            margin-top: 1ex;
        }
        QGroupBox:enabled {
            border: 3px solid green;
        }
        QGroupBox::title {
            subcontrol-origin: margin;
            left: 1ex;
        }''')


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = Template()
    window.show()
    sys.exit(app.exec_())