Fix epochs.plot() scrollbar issue (#13654)

Author: cbrnr

doc/changes/dev/13654.bugfix.rst

@@ -0,0 +1 @@
+Fix bug in :meth:`mne.Epochs.plot` where clicking on the scrollbar would not scroll to the last epoch, by `Clemens Brunner`_.

mne/viz/_mpl_figure.py

@@ -1754,7 +1754,7 @@ def _check_update_hscroll_clicked(self, event):
         )
         time = np.clip(time, self.mne.first_time, max_time)
         if self.mne.is_epochs:
-            ix = np.searchsorted(self.mne.boundary_times[1:], time)
+            ix = np.searchsorted(self.mne.boundary_times[1:], time, side="right")
             time = self.mne.boundary_times[ix]
         if self.mne.t_start != time:
             self.mne.t_start = time

mne/viz/tests/test_epochs.py

@@ -136,6 +136,10 @@ def test_plot_epochs_clicks(epochs, epochs_full, capsys, browser_backend):
     # test clicking scrollbars
     fig._fake_click((0.5, 0.5), ax=fig.mne.ax_vscroll)
     fig._fake_click((0.5, 0.5), ax=fig.mne.ax_hscroll)
+    # clicking near right edge in hscroll should reach final epoch window
+    fig._fake_click((0.99, 0.5), ax=fig.mne.ax_hscroll)
+    max_t_start = fig.mne.n_times / fig.mne.info["sfreq"] - fig.mne.duration
+    assert fig.mne.t_start == pytest.approx(max_t_start)
     # test moving bad epoch offscreen
     fig._fake_keypress("right")  # move right
     x = fig.mne.traces[0].get_xdata()[-3]