[Gui] modernize some connect() settings

- addresses #6166

src/Gui/ProgressDialog.cpp

@@ -36,7 +36,6 @@
 
 using namespace Gui;
 
-
 namespace Gui {
 struct SequencerDialogPrivate
 {
@@ -49,7 +48,6 @@ struct SequencerDialogPrivate
 };
 }
 
-
 SequencerDialog* SequencerDialog::_pclSingleton = nullptr;
 
 SequencerDialog* SequencerDialog::instance()
@@ -305,7 +303,7 @@ ProgressDialog::ProgressDialog (SequencerDialog* s, QWidget * parent)
     m_taskbarButton = nullptr;
     m_taskbarButton = nullptr;
 #endif
-    connect(this, SIGNAL(canceled()), this, SLOT(onCancel()));
+    connect(this, &Gui::ProgressDialog::canceled, this, &ProgressDialog::onCancel);
 }
 
 ProgressDialog::~ProgressDialog ()