Set border for QSpinBox when focused

Question

For already existed Qt project I'd like set border for focused widgets through qss-fle. But I faced out with some unexpected result. When I change border of QSpinBox (and QDoubleSpinBox) border will change as I expect but up-button and down-button change too and look ugly.

Here is my style definition (full example available here):

QSpinBox:focus
{
    border-width: 2px;
    border-style: solid;
    border-color: green;
}

My question is: how to change appearance of border and simultaneously preserve appearance of up-button and down-button. Solution what I am looking for shouldn't be cross platform or cross version.

My environment:
- KUbuntu 15.10 (amd64);
- Qt 5.4 (x64).

Update:

Here is one more example with another style:

QSpinBox
{
    border-width: 2px;
    border-style: solid;
    border-color : red;
}

QSpinBox:hover
{
    border-width: 2px;
    border-style: solid;
    border-color: blue;
}

The widget looks like this:

Answer 1

When you apply a style sheet to the QSpinBox, this widget is completely painted using the QStyleSheetStyle (this class is not part of the public API).

So you have to either style your spin box completely, including the up/down buttons or not to use the style sheet at all.

That up/down buttons are not separated widgets, so you can't apply a different style to them.

So I suggest to subclass the QSpinBox and reimplement the paintEvent() method. In your paintEvent() method you will just call it's default implementation and than you will draw a rectangle around.