Focus on QLabel twitches text

[AlaaM]

Whenever there's focus on a QLabel, the text inside twitches a little to the bottom. Take a look at this picture:
http://i90.photobucket.com/albums/k274/alaa_137/qlabel_zps3aheyglu.png
Here every digit is a separate QLabel.
Notice that the first digit on the left is twitched a little to the bottom because it has focus. Also when I move focus to another digit, then the 1st digit is still twitched, and the newly focused digit gets twitched as well.

Why is this happening? Can I disable this?

Thanks

[raven-worx]

@AlaaM
Operating system?
Qt version?
Using stylesheets or anything?
Any interaction with the widget's QStyle?

[AlaaM]

Operating system: Ubuntu 14.04
Qt 5.5.1
Was using the following stylesheet:

QString("QLabel:focus{"
             "outline: 0;"
             "background-color: #" BACKGROUND  "; "
             "color: #"            FOREGROUND  "; "
         "} "
) 

But seems that the issue happens with and without it.

Nothing with the widget's QStyle

[raven-worx]

@AlaaM
Did you build Qt yourself?
have you changed anything regarding HARFBUZZ?

[AlaaM]

@raven-worx I did not build Qt myself. I downloaded QtCreator and Qt libraries.
I don't know what HARFBUZZ is so I guess I didn't change it.

I don't think this has something to do with the compilation...

I think it's either Ubuntu's default, or something in my code.
I can try to change the QLabel to something else (say QTextEdit) and see what happens.

[elveatles]

Does it still twitch if you don't use the stylesheet?

[AlaaM]

@elveatles Yes. As I said: seems that the issue happens with and without it.

[raven-worx]

@AlaaM said:

I don't know what HARFBUZZ is so I guess I didn't change it.

HARFBUZZ is used for text rendering in Qt.
But i do not know if on Ubuntu (or in general in Linux) the system lib is used or the built-in version of Qt is used by default.

Maybe someone else can confirm/disprove this?

But updating the harfbuzz lib on your system is worth a shot i guess.

[AlaaM]

I can't believe I didn't think of this before. Here's the solution:

labels[i]->setStyleSheet(QString("QLabel{"
                                     "padding: 0px"
                                 "}"
                                )
                         );

(or any other number for padding)

This disables the twitching.