It would be convenient to be able to set the window flags immediately to a window that is shown.

Currently the window is hidden and the it must be re-shown, this causes a "flash" effect when the window is hidden and shown rapidly.

The problem is demonstratable with the following code:
#include <QtGui>
#include <QDebug>

class CustomWidget : public QWidget
{ Q_OBJECT
public:
CustomWidget(QWidget* parent=0) : QWidget(parent)
{ }

public slots:
void aSlot()

{ qDebug() << "aSlot invoked"; setWindowFlags( Qt::Tool ); show(); }

};

#include "main.moc"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

CustomWidget wid;
wid.show();

QTimer::singleShot(2000, &wid, SLOT(aSlot()));

return app.exec();
}