Three connects paired a zero-argument signal with a slot that has a default-valued parameter (e.g. void applyEnable(bool = true)).

Default arguments aren't part of a function's pointer-to-member type, so &Class::slot has a type requiring the argument regardless of its
default value -- incompatible with a signal providing none, and &Class::slot alone won't compile against these signals at all.
When migrating to the modern member pointer connect, replaced  with a lambda that calls the slot with no arguments, letting
the default apply exactly as before.

- SelectAutonumW::applyEnable(bool = true), connected to each  NumPartEditorW's changed() signal in both setContext() and
  on_add_button_clicked(). The corresponding disconnect() in on_remove_button_clicked() is removed rather than reimplemented: a
  lambda-based connection can't be matched and removed by a  separately-written disconnect() call, and the explicit disconnect
  was already redundant -- the very next line deletes the part object, which Qt automatically disconnects on destruction (the same
  guarantee setContext()'s own qDeleteAll() cleanup already relies  on).
- PartText::adjustItemPosition(int = 0), connected to QTextDocument::contentsChanged().
- ExportDialog::slot_changeFilesExtension(bool = false), connected to ExportPropertiesWidget::formatChanged().

sources/exportdialog.cpp

@@ -98,7 +98,7 @@ ExportDialog::ExportDialog(
 	layout -> addWidget(buttons);
 	
 	// connexions signaux/slots
-	connect(epw,     SIGNAL(formatChanged()),       this, SLOT(slot_changeFilesExtension()));
+	connect(epw, &ExportPropertiesWidget::formatChanged, this, [this]() { slot_changeFilesExtension(); });
 	connect(epw, &ExportPropertiesWidget::exportedAreaChanged, this, &ExportDialog::slot_changeUseBorder);
 	connect(buttons, &QDialogButtonBox::accepted, this, &ExportDialog::slot_export);
 	connect(buttons, &QDialogButtonBox::rejected, this, &ExportDialog::reject);