Question

I want to remove the “?”-button from a Qt dialog like explained here, but somehow it doesn’t work.

This is my code:

Qt::WindowFlags flags;
flags = (Qt::Dialog | Qt::WindowStaysOnTopHint) & 
          ~Qt::WindowContextHelpButtonHint;
setWindowFlags( flags );

I think that there is something wrong with the bitwise operators, but I don’t know what..

Answer 1

This works fine for me:

QDialog *dialog = new QDialog;
Qt::WindowFlags flags(Qt::WindowTitleHint);
dialog->setWindowFlags(flags);

The most common way, however, is to pass the flags in the constructor:

QDialog *dialog = new QDialog(0, Qt::WindowTitleHint);

EDIT: I think there is a misunderstanding about the QFlags operators (see comments below). This example might clear it up:

Qt::WindowFlags flags(Qt::Dialog | Qt::WindowStaysOnTopHint);
qDebug() << flags.testFlag(Qt::WindowContextHelpButtonHint); // false because the flag hasn't been added
flags = flags | Qt::WindowContextHelpButtonHint;
qDebug() << flags.testFlag(Qt::WindowContextHelpButtonHint); // true because it has been added
flags = flags & ~Qt::WindowContextHelpButtonHint;
qDebug() << flags.testFlag(Qt::WindowContextHelpButtonHint); // false because it has been removed

The penultimate line of code removes Qt::WindowContextHelpButtonHint from flags. It does not add a “negative” flag.

At least that is my understanding.