How can I resize QMessageBox?

Question

I have a QMessageBox which I'd like it to be bigger. It's a simple QMessageBox with two standard buttons, Ok and Cancel. The problem is that it is very small for my application's purposes. Code shows like this:

QMessageBox msg; msg.setText("Whatever"); msg.setStandardButtons(QMessageBox::Ok | QMessageBox::Cancel); msg.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);  int ret = msg.exec(); switch (ret) {   case QMessageBox::Ok:       ui->textEdit->clear();       break;   case QMessageBox::Cancel:       break;} 

I tried several ways to increase the size:

msg.setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);  msg.setSizePolicy(QSizePolicy::Maximum,QSizePolicy::Maximum);  msg.setFixedHeight(600); msg.setFixedWidth(600); 

I even cleared and rebuilt, and it compiles everything but nothing take effect...

Do you have any idea on how to set QMessageBox size "by hand"? Thanks.

Answer 1

You can edit the css of the label:

msg.setStyleSheet("QLabel{min-width: 700px;}"); 

You can similarly edit the css of the buttons to add a margin or make them bigger.

For example:

msg.setStyleSheet("QLabel{min-width:500 px; font-size: 24px;} QPushButton{ width:250px; font-size: 18px; }"); 

There is also a trick mentioned:

QSpacerItem* horizontalSpacer = new QSpacerItem(800, 0, QSizePolicy::Minimum, QSizePolicy::Expanding); QGridLayout* layout = (QGridLayout*)msg.layout(); layout->addItem(horizontalSpacer, layout->rowCount(), 0, 1, layout->columnCount()); 

But this doesn't seem to work for everyone.

Answer 2

coyotte508's answer caused my layout to be horribly off center and at different widths it was cut off. In searching around further I found this thread which explains a better solution.

In essence the layout of a messagebox is a grid, so you can add a SpacerItem to it to control the width. Here's the c++ code sample from that link:

QMessageBox msgBox; QSpacerItem* horizontalSpacer = new QSpacerItem(500, 0, QSizePolicy::Minimum, QSizePolicy::Expanding); msgBox.setText( "SomText" ); QGridLayout* layout = (QGridLayout*)msgBox.layout(); layout->addItem(horizontalSpacer, layout->rowCount(), 0, 1, layout->columnCount()); msgBox.exec();