[Gui] remove misleading button from About Dialog

- the help button in the title bar had no function but I remember people asked in the forum what it does. Since we don't use it, remove it

src/Gui/Splashscreen.cpp

@@ -223,6 +223,10 @@ AboutDialog::AboutDialog(bool showLic, QWidget* parent)
 
     setModal(true);
     ui->setupUi(this);
+
+    // remove the automatic help button in dialog title since we don't use it
+    setWindowFlag(Qt::WindowContextHelpButtonHint, false);
+
     layout()->setSizeConstraint(QLayout::SetFixedSize);
     QRect rect = QApplication::primaryScreen()->availableGeometry();