Initial notes to see call flow

IPython/external/qt_for_kernel.py

@@ -95,6 +95,7 b' def matplotlib_options(mpl):'
                           mpqt)
 
 def get_options():
+    print(f'`get_options` called with {os.environ.get("QT_API", None)=}')
     """Return a list of acceptable QT APIs, in decreasing order of preference."""
     #already imported Qt somewhere. Use that
     loaded = loaded_api()
@@ -129,5 +130,7 b' def get_options():'
 
 
 api_opts = get_options()
+print(f'Importing `IPython.terminal.pt_inputhooks.qt` with {api_opts=}')
 QtCore, QtGui, QtSvg, QT_API = load_qt(api_opts)
+print(f'Loaded Qt with {QT_API=}')
 enum_helper = enum_factory(QT_API, QtCore)

IPython/terminal/interactiveshell.py

@@ -711,6 +711,7 b' class TerminalInteractiveShell(InteractiveShell):'
 
     active_eventloop = None
     def enable_gui(self, gui=None):
+        print(f'Someone called `enable_gui` with {gui=}.')
         if gui and (gui not in {"inline", "webagg"}):
             # This hook runs with each cycle of the `prompt_toolkit`'s event loop.
             self.active_eventloop, self._inputhook = get_inputhook_name_and_func(gui)

IPython/terminal/pt_inputhooks/__init__.py

@@ -41,6 +41,7 b' class UnknownBackend(KeyError):'
 
 
 def get_inputhook_name_and_func(gui):
+    print(f'`get_inputhook_name_and_func` called with {gui=}')
     if gui in registered:
         return gui, registered[gui]
 

IPython/terminal/pt_inputhooks/qt.py

@@ -57,7 +57,7 b' def inputhook(context):'
         QtCore.QTimer.singleShot(0, _reclaim_excepthook)
 
     event_loop = QtCore.QEventLoop(app)
-
+    print(f'`inputhook` running Qt {QtCore.qVersion()} event loop.\r')
     if sys.platform == 'win32':
         # The QSocketNotifier method doesn't appear to work on Windows.
         # Use polling instead.