Enh browserfig UI events

mne/viz/ui_events.py

@@ -233,6 +233,7 @@ def _get_event_channel(fig):
     import matplotlib
 
     from ._brain import Brain
+    from ._figure import BrowserBase
     from .evoked_field import EvokedField
 
     # Create the event channel if it doesn't exist yet
@@ -263,9 +264,13 @@ def delete_event_channel(event=None, *, weakfig=weakfig):
         # Hook up the above callback function to the close event of the figure
         # window. How this is done exactly depends on the various figure types
         # MNE-Python has.
-        _validate_type(fig, (matplotlib.figure.Figure, Brain, EvokedField), "fig")
+        _validate_type(
+            fig, (matplotlib.figure.Figure, Brain, EvokedField, BrowserBase), "fig"
+        )
         if isinstance(fig, matplotlib.figure.Figure):
             fig.canvas.mpl_connect("close_event", delete_event_channel)
+        elif isinstance(fig, BrowserBase):
+            fig.mne.viewbox.destroyed.connect(delete_event_channel)
         else:
             assert hasattr(fig, "_renderer")  # figures like Brain, EvokedField, etc.
             fig._renderer._window_close_connect(delete_event_channel, after=False)