In some dialogs, have *no* auto-default buttons on macOS.

In macOS dialogs, there's a default button, which is the button that
Enter/Return activates, and that Enter/Return *always* activates,
*regardless* of what button has the input focus.  To activate the button
that has the input focus, you use the space bar.

To implement that, we need to disable auto-default on all buttons,
including the Cancel button.

Put in a comment explaining all this.

We may want to do this in all alert boxes, and possibly all dialogs with
buttons.

Change-Id: I214dd2870a9720ea705d8db39adc5b6af2003fb1
Reviewed-on: https://code.wireshark.org/review/26629
Reviewed-by: Guy Harris <guy@alum.mit.edu>

2 files changed, 53 insertions, 2 deletions

diff --git a/ui/qt/capture_file_dialog.cpp b/ui/qt/capture_file_dialog.cpp
index 56e157a3e7..957aca23ca 100644
--- a/ui/qt/capture_file_dialog.cpp
+++ b/ui/qt/capture_file_dialog.cpp
@@ -155,7 +155,31 @@ check_savability_t CaptureFileDialog::checkSaveAsWithComments(QWidget *
     }
 
 #if defined(Q_OS_MAC)
-    discard_button->setAutoDefault(false);
+    /*
+     * In macOS, the "default button" is not necessarily the button that
+     * has the input focus; Enter/Return activates the default button, and
+     * the spacebar activates the button that has the input focus, and
+     * they might be different buttons.
+     *
+     * In a "do you want to save" dialog, for example, the "save" button
+     * is the default button, and the "don't save" button has the input
+     * focus, so you can press Enter/Return to save or space not to save
+     * (or Escape to dismiss the dialog).
+     *
+     * In Qt terms, this means "no auto-default", as auto-default makes the
+     * button with the input focus the default button, so that Enter/Return
+     * will activate it.
+     */
+    QList<QAbstractButton *> buttons = msg_dialog.buttons();
+    for (int i = 0; i < buttons.size(); ++i) {
+        QPushButton *button = static_cast<QPushButton *>(buttons.at(i));;
+        button->setAutoDefault(false);
+    }
+
+    /*
+     * It also means that the "don't save" button should be the one
+     * initially given the focus.
+     */
     discard_button->setFocus();
 #endif
 
diff --git a/ui/qt/main_window.cpp b/ui/qt/main_window.cpp
index 875d768595..89231ce39f 100644
--- a/ui/qt/main_window.cpp
+++ b/ui/qt/main_window.cpp
@@ -78,6 +78,7 @@ DIAG_ON(frame-larger-than=)
 #include <QActionGroup>
 #include <QDesktopWidget>
 #include <QKeyEvent>
+#include <QList>
 #include <QMessageBox>
 #include <QMetaObject>
 #include <QMimeData>
@@ -1804,7 +1805,33 @@ bool MainWindow::testCaptureFileClose(QString before_what, FileCloseContext cont
             discard_button = msg_dialog.addButton(discard_button_text, QMessageBox::DestructiveRole);
 
 #if defined(Q_OS_MAC)
-            discard_button->setAutoDefault(false);
+            /*
+             * In macOS, the "default button" is not necessarily the
+             * button that has the input focus; Enter/Return activates
+             * the default button, and the spacebar activates the button
+             * that has the input focus, and they might be different
+             * buttons.
+             *
+             * In a "do you want to save" dialog, for example, the
+             * "save" button is the default button, and the "don't
+             * save" button has the input focus, so you can press
+             * Enter/Return to save or space not to save (or Escape
+             * to dismiss the dialog).
+             *
+             * In Qt terms, this means "no auto-default", as auto-default
+             * makes the button with the input focus the default button,
+             * so that Enter/Return will activate it.
+             */
+            QList<QAbstractButton *> buttons = msg_dialog.buttons();
+            for (int i = 0; i < buttons.size(); ++i) {
+                QPushButton *button = static_cast<QPushButton *>(buttons.at(i));;
+                button->setAutoDefault(false);
+            }
+
+            /*
+             * It also means that the "don't save" button should be the one
+             * initially given the focus.
+             */
             discard_button->setFocus();
 #endif