mainwindow.h
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
public slots:
    void slotClear();

private:
    QLineEdit* line1;
    QLineEdit* line2;
//...
};

mainwindow.cpp
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent), ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QVBoxLayout* mainLayout = new QVBoxLayout;

    QFormLayout* form = new QFormLayout;
    line1 = new QLineEdit;
    form->addRow(tr("Line 1: "), line1);
    line2 = new QLineEdit;
    form->addRow(tr("Line 2:"), line2);

    QPushButton* button = new QPushButton;
    mainLayout->addLayout(form);
    mainLayout->addWidget(button);

    QWidget* centralWid = new QWidget(this);
    centralWid->setLayout(mainLayout);
    this->setCentralWidget(centralWid);

    connect(button, SIGNAL(clicked()), this, SLOT(slotClear()));
}

void MainWindow::slotClear()
{
    line1->clear();
    line2->clear();
}
//...

This code is set-up to clear the text in two QLineEdit objects when a button is clicked. Unfortunately this isn't the case, randomly only one of the two QLineEdit objects are cleared.

Additionally entering text in one line, switching to another line and entering text there, and then switching back to the original line results in the original text being erased once the field is clicked (note, the button was never clicked).

Reproducible: Always

Steps to Reproduce:
1. Create a new project
2. Add two QLineEdit objects and a QPushButton object to a main window
3. Connect the QPushButton clicked() signal to the QLineEdit objects clear() slots.
4. Run the application, enter text in both QLineEdit objects and click the button.
Actual Results:  
Both QLineEdit objects are not cleared of text.

Expected Results:  
Both QLineEdit objects should have no text.

Calling the function QLineEdit::setText("") with an empty string has the same results.