diff --git a/larray_editor/api.py b/larray_editor/api.py
index 08fd80a..eac1809 100644
--- a/larray_editor/api.py
+++ b/larray_editor/api.py
@@ -57,12 +57,16 @@ def _show_dialog(app_name, create_dialog_func, *args, **kwargs):
     # (see issue #253) or after showing matplotlib figures (see issue #261).
 
     # We have not found any way to explicitly check whether the main event loop
-    # is already running, so we now assume that if the parent window is not
+    # is already running (*), so we now assume that if the parent window is not
     # a descendant of our own MappingEditor, no event loop is running, as it is
     # unlikely another Qt application calls the *api functions* instead of
     # embedding the widget. Note that jupyter qtconsole works, because the
     # Python kernel process is not the same as the process running the
     # interface, so QApplication.instance() returns None in the kernel process.
+
+    # (*) QEventLoop has an isRunning() method, but QCoreApplication *acts*
+    #     as an event loop but does not inherit from QEventLoop, and it lacks
+    #     the method.
     if parent is None:
         # We do not use install_except_hook/restore_except_hook so that we can restore the hook actually used when
         # this function is called instead of the one which was used when the module was loaded.
diff --git a/larray_editor/tests/test_api_larray.py b/larray_editor/tests/test_api_larray.py
index 7f9a323..17e8ad1 100644
--- a/larray_editor/tests/test_api_larray.py
+++ b/larray_editor/tests/test_api_larray.py
@@ -100,6 +100,15 @@ def make_demo(width=20, ball_radius=5, path_radius=5, steps=30):
     return la.maximum(ball_radius - la.sqrt((x - ball_center_x) ** 2 + (y - ball_center_y) ** 2), 0).transpose(x, y)
 
 
+def test_matplotlib_show_interaction():
+    import matplotlib.pyplot as plt
+
+    arr = la.ndtest((3, 4))
+    arr.plot()
+    plt.show()
+    edit()
+
+
 demo = make_demo(9, 2.5, 1.5)
 sphere = make_sphere(9, 4)
 extreme_array = la.Array([-la.inf, -1, 0, la.nan, 1, la.inf])
@@ -208,3 +217,5 @@ def test_run_editor_on_exception(local_arr):
 # run_editor_on_exception(usercode_traceback=False, usercode_frame=False)
 
 # test_run_editor_on_exception(arr2)
+
+test_matplotlib_show_interaction()