[FIXED] How to dissable the focus indication in stylesheet

Issue

When my QDoubleSpinBox is focused, it gets a blue outline to it (in "Fusion" style):

How do I turn this off?

Solution

Doing this with stylesheets only is doable, but has an important drawback: styling complex widgets like a QSpinBox requires to correctly set all sub control properties.

The basic solution is to set the border for the widget:

QSpinBox {
    border: 1px inset palette(mid);
    border-radius: 2px;
}

Keep in mind that offering proper visible response of the focus is really important; you might not like the "glow" (and color) the Fusion style offers, but nonetheless it should always be visible when a widget has focus or not, even if it has a blinking text cursor. You can do that by specifying a slightly different color with the :focus selector:

QSpinBox:focus {
    border: 1px inset palette(dark);
}

Unfortunately, as explained in the beginning, this has an important drawback: as soon as the stylesheet is applied, the widget painting falls back to the basic primitive methods (the spinbox on the right uses the stylesheet above):

Unfortunately, there's almost no direct way to restore the default painting of the arrows, as using the stylesheet prevents that. So, the only solution is to provide the properties for the controls as explained in the examples about customizing QSpinBox.

There is an alternative, though, using QProxyStyle. The trick is to intercept the control in the drawComplexControl() implementation and remove the State_HasFocus flag of the option before calling the default implementation.
In the following example, I also checked the focus before removing the flag in order to provide sufficient visual feedback, and I also removed the State_MouseOver flag which shows the glowing effect when hovering.

class Proxy(QtWidgets.QProxyStyle):
    def drawComplexControl(self, cc, opt, qp, widget=None):
        if cc == self.CC_SpinBox:
            opt = QtWidgets.QStyleOptionSpinBox(opt)
            if opt.state & self.State_HasFocus:
                opt.palette.setColor(QtGui.QPalette.Window, 
                    opt.palette.color(QtGui.QPalette.Window).darker(100))
            else:
                opt.palette.setColor(QtGui.QPalette.Window, 
                    opt.palette.color(QtGui.QPalette.Window).lighter(125))
            opt.state &= ~(self.State_HasFocus | self.State_MouseOver)
        super().drawComplexControl(cc, opt, qp, widget)

# ...
app = QtWidgets.QApplication(sys.argv)
app.setStyle(Proxy())
# ...

Note that the above "color correction" only works for Fusion style and other styles that use the Window palette role for painting the border. For instance, the Windows style doesn't consider it at all, or you might want to use higher values of darker() or lighter() in order to provide better differentiation.

Answered By - musicamante