standarddialogs: Don't assume QMessageBox::exec() returns clicked role

When adding custom buttons to a QMessageBox the return value of exec()
as well as result() is not a StandardButton value, but instead an opaque
value, and the documentation says to use clickedButton() to determine
which button was clicked.

Pick-to: 6.6 6.5
Change-Id: Ib47a218989b4dcb5d51f648bc55bc02399bae602
Reviewed-by: Oliver Eftevaag <oliver.eftevaag@qt.io>

1 files changed, 7 insertions, 5 deletions

diff --git a/examples/widgets/dialogs/standarddialogs/dialog.cpp b/examples/widgets/dialogs/standarddialogs/dialog.cpp
index e46c337888..67fb615794 100644
--- a/examples/widgets/dialogs/standarddialogs/dialog.cpp
+++ b/examples/widgets/dialogs/standarddialogs/dialog.cpp
@@ -455,13 +455,15 @@ void Dialog::warningMessage()
                               tr("Delete the only copy of your movie manuscript?"), { }, this);
     msgBox.setInformativeText(tr("You've been working on this manuscript for 738 days now. Hang in there!"));
     msgBox.setDetailedText("\"A long time ago in a galaxy far, far away....\"");
-    msgBox.addButton(tr("&Keep"), QMessageBox::AcceptRole);
-    msgBox.addButton(tr("Delete"), QMessageBox::DestructiveRole);
-    if (msgBox.exec() == QMessageBox::AcceptRole)
+    auto *keepButton = msgBox.addButton(tr("&Keep"), QMessageBox::AcceptRole);
+    auto *deleteButton = msgBox.addButton(tr("Delete"), QMessageBox::DestructiveRole);
+    msgBox.exec();
+    if (msgBox.clickedButton() == keepButton)
         warningLabel->setText(tr("Keep"));
-    else
+    else if (msgBox.clickedButton() == deleteButton)
         warningLabel->setText(tr("Delete"));
-
+    else
+        warningLabel->setText("");
 }
 
 void Dialog::errorMessage()