Fix warnings about signal-slot connection in filetree example.

Task-number: QTBUG-31079

Change-Id: I2696834f70bd0db05c9d70759b81159fabe561fd
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>

examples/xmlpatterns/filetree/mainwindow.cpp

@@ -81,9 +81,9 @@ MainWindow::MainWindow() : m_fileTree(m_namePool)
 //! [0]
 
 //! [2]
-void MainWindow::on_queryBox_currentIndexChanged()
+void MainWindow::on_queryBox_currentIndexChanged(const QString &currentText)
 {
-    QFile queryFile(":/queries/" + queryBox->currentText());
+    QFile queryFile(":/queries/" + currentText);
     queryFile.open(QIODevice::ReadOnly);
 
     queryEdit->setPlainText(QString::fromLatin1(queryFile.readAll()));

examples/xmlpatterns/filetree/mainwindow.h

@@ -58,7 +58,7 @@ public:
 private slots:
     void on_actionOpenDirectory_triggered();
     void on_actionAbout_triggered();
-    void on_queryBox_currentIndexChanged();
+    void on_queryBox_currentIndexChanged(const QString &);
 
 private:
     void loadDirectory(const QString &directory);