fix: prevent top-level dock areas to be destroyed with [X] button

bec_widgets/cli/server.py

@@ -249,6 +249,12 @@ def main():
             def sigint_handler(*args):
                 # display message, for people to let it terminate gracefully
                 print("Caught SIGINT, exiting")
+                # first hide all top level windows
+                # this is to discriminate the cases between "user clicks on [X]"
+                # (which should be filtered, to not close -see BECDockArea-)
+                # or "app is asked to close"
+                for window in app.topLevelWidgets():
+                    window.hide()  # so, we know we can exit because it is hidden
                 app.quit()
 
             signal.signal(signal.SIGINT, sigint_handler)

bec_widgets/widgets/containers/dock/dock_area.py

@@ -423,6 +423,17 @@ class BECDockArea(BECWidget, QWidget):
         self.dock_area.deleteLater()
         super().cleanup()
 
+    def closeEvent(self, event):
+        if self.parent() is None:
+            # we are at top-level (independent window)
+            if self.isVisible():
+                # we are visible => user clicked on [X]
+                # (when closeEvent is called from shutdown procedure,
+                # everything is hidden first)
+                # so, let's ignore "close", and do hide instead
+                event.ignore()
+                self.setVisible(False)
+
     def close(self):
         """
         Close the dock area and cleanup.