Merge pull request #528 from ispyisail/fix/project-props-dialog-modality

Merged as discussed in #527 
Thanks @ispyisail

sources/qetapp.cpp

@@ -1993,7 +1993,10 @@ void QETApp::configureQET()
 	// cree le dialogue
 	ConfigDialog cd;
 	cd.setWindowTitle(tr("Configurer QElectroTech", "window title"));
-	cd.setWindowModality(Qt::WindowModal);
+	// ApplicationModal so no other window can dispatch events while the dialog
+	// holds raw pointers derived from the current project list.  Same class of
+	// bug as ProjectPropertiesDialog — see issue #527.
+	cd.setWindowModality(Qt::ApplicationModal);
 	cd.addPage(new GeneralConfigurationPage());
 	cd.addPage(new NewDiagramPage());
 	cd.addPage(new ExportConfigPage());

sources/ui/projectpropertiesdialog.cpp

@@ -63,7 +63,13 @@ ProjectPropertiesDialog::~ProjectPropertiesDialog ()
 */
 void ProjectPropertiesDialog::exec()
 {
-	m_properties_dialog->setWindowModality(Qt::WindowModal);
+	// ApplicationModal (not WindowModal) so no other window — including other
+	// MDI subwindows — can dispatch events while the dialog holds raw
+	// QETProject* pointers in its config pages.  WindowModal only blocks the
+	// parent ProjectView; the rest of the MDI area stays live, which allowed
+	// new_project / close_project to replace the project under the dialog
+	// and cause a SIGSEGV.  See issue #527.
+	m_properties_dialog->setWindowModality(Qt::ApplicationModal);
 	m_properties_dialog -> exec();
 }