Revamp QtWidgets/DragAndDrop examples to C++11

Introduce nullptr and replace foreach with new C++11 range based for
loops. Minor fixups of signals, file dialog usage.

Apply the same changes to the ItemViews/puzzle example since it
shares parts of the code with DragAndDrop/puzzle. Make some
changes to both examples to that the diff of the two becomes
small for easier comparison.

Task-number: QTBUG-60635
Change-Id: I8af824229ebac24d6ec151eae92176d227695490
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 3 insertions, 3 deletions

diff --git a/examples/widgets/draganddrop/dropsite/dropsitewindow.cpp b/examples/widgets/draganddrop/dropsite/dropsitewindow.cpp
index dc865ac171..28a42ee614 100644
--- a/examples/widgets/draganddrop/dropsite/dropsitewindow.cpp
+++ b/examples/widgets/draganddrop/dropsite/dropsitewindow.cpp
@@ -88,8 +88,8 @@ DropSiteWindow::DropSiteWindow()
     buttonBox->addButton(clearButton, QDialogButtonBox::ActionRole);
     buttonBox->addButton(quitButton, QDialogButtonBox::RejectRole);
 
-    connect(quitButton, &QAbstractButton::pressed, this, &QWidget::close);
-    connect(clearButton, &QAbstractButton::pressed, dropArea, &DropArea::clear);
+    connect(quitButton, &QAbstractButton::clicked, this, &QWidget::close);
+    connect(clearButton, &QAbstractButton::clicked, dropArea, &DropArea::clear);
 //! [constructor part4]
 
 //! [constructor part5]
@@ -113,7 +113,7 @@ void DropSiteWindow::updateFormatsTable(const QMimeData *mimeData)
 //! [updateFormatsTable() part1]
 
 //! [updateFormatsTable() part2]
-    foreach (QString format, mimeData->formats()) {
+    for (const QString &format : mimeData->formats()) {
         QTableWidgetItem *formatItem = new QTableWidgetItem(format);
         formatItem->setFlags(Qt::ItemIsEnabled);
         formatItem->setTextAlignment(Qt::AlignTop | Qt::AlignLeft);