UnderlinedItem.py

from PySide.QtCore import *
from PySide.QtGui import *

lineWidth = 3
rows = 4
columns = 6
color = 'red'

class UnderlinedItemClass(QWidget):
    def __init__(self):
        super(UnderlinedItemClass, self).__init__()
        self.ly = QVBoxLayout(self)
        self.vly = QHBoxLayout()
        self.select = QPushButton('Select Items')
        self.select.clicked.connect(self.select_items)
        self.unselect = QPushButton('Unselect Items')
        self.unselect.clicked.connect(lambda : self.select_items(False))
        self.vly.addWidget(self.select)
        self.vly.addWidget(self.unselect)

        self.ly.addLayout(self.vly)

        self.table = QTableWidget()
        self.ly.addWidget(self.table)
        self.fill_table()
        self.resize(700,400)

    def fill_table(self):
        self.table.clear()
        self.table.setColumnCount(columns)
        for i in range(rows):
            self.table.insertRow(self.table.rowCount())
            for j in range(columns):
                w = ItemWidget()
                self.table.setCellWidget(i, j, w)

    def select_items(self, sel=True):
        for ind in  self.table.selectedIndexes():
            if sel:
                self.table.cellWidget(ind.row(), ind.column()).select()
            else:
                self.table.cellWidget(ind.row(), ind.column()).unselect()


class ItemWidget(QWidget):
    def __init__(self):
        super(ItemWidget, self).__init__()
        self.content_ly = QVBoxLayout(self)
        self.content_ly.setContentsMargins(0,0,0,0)
        self.text = QLabel()
        self.text.setStyleSheet('padding:3px;padding-bottom:-2px;')
        self.content_ly.addWidget(self.text)

        self.line = QFrame()
        self.line.setMaximumHeight(lineWidth)
        self.line.setMinimumHeight(lineWidth)
        self.content_ly.addWidget(self.line)

        self.setText('ITEM')

    def setText(self, text):
        self.text.setText(text)

    def select(self):
        # self.line.setStyleSheet('QWidget{border:none; border-bottom: 2px solid red;}')
        self.line.setStyleSheet('background-color:%s;' % color)

    def unselect(self):
        self.line.setStyleSheet('')

if __name__ == '__main__':
    app = QApplication([])
    w = UnderlinedItemClass()
    w.show()
    app.exec_()