How to highlight a QWidget

[AndreiTuicu]

Hello everyone! Here is my question:

I've derived the QToolButton so that buttons in QToolBar can be accessed by tabbing, but when it gains focus it is not highlighted like when i hover with the cursor over it. I've overriden the focusInEvent function, but when it comes to actually highlighting the button I don't know what property/attribute to set or what method to call.

Here is what it looks like when I hover with the cursor over the button:
example1.png
How can I achieve this by replacing the line marked?

Here is what is currently happening:
example2.png

void focusInEvent(QFocusEvent* e){
        if(e->gotFocus() && e->reason() == Qt::TabFocusReason){
            setGraphicsEffect(new QGraphicsColorizeEffect());  //line to be replaced
            }
        QToolButton::focusInEvent(e);
    }

void focusInEvent(QFocusEvent* e){
        if(e->gotFocus() && e->reason() == Qt::TabFocusReason){
            setGraphicsEffect(new QGraphicsColorizeEffect());  //line to be replaced
            }
        QToolButton::focusInEvent(e);
    }

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Thank you for your help!