some fixes again

python_app/gui/controllers/app_window_preprocess_mixin.py

@@ -117,6 +117,13 @@ class AppWindowPreprocessMixin:
                 details=self._capture_state_details(),
             )
             return
+        # One shared re-entrancy guard for BOTH the GUI button and the GPIO trigger:
+        # this capture spins the Qt event loop (stop/start run, dialogs), so a second
+        # request from either source must not start a nested capture.
+        if self._control_button_busy:
+            self._log("Tmp reference capture already in progress; ignoring duplicate request.")
+            return
+        self._control_button_busy = True
 
         pipeline_was_running = self._supervisor.is_running()
         pipeline_was_paused = False
@@ -178,6 +185,7 @@ class AppWindowPreprocessMixin:
         finally:
             if pipeline_was_paused:
                 self._start_run()
+            self._control_button_busy = False
 
     def _ensure_preprocess_dialog(self) -> PreprocessDialog:
         """Create preprocessing dialog lazily and wire its signals once."""