From 840035ce918889273937ff43c1083a8637fb8bc0 Mon Sep 17 00:00:00 2001
From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
Date: Thu, 10 Sep 2020 23:26:00 -0400
Subject: [PATCH 1/2] nbagg: Use OutputArea event to trigger figure close.

When converting from jQuery to vanilla JavaScript, the trigger for the
figure closure was set to a non-existent event name, as the 'remove'
event is jQuery-specific.

As there is no DOM node removal event (unless using MutationObserver),
connect this handler to the notebook's `Cell` `OutputArea`'s 'cleared'
event. This is triggered both by re-running a cell, and by using the
Clear Output menu option.

Fixes #18447.
---
 .../backends/web_backend/js/nbagg_mpl.js         | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/lib/matplotlib/backends/web_backend/js/nbagg_mpl.js b/lib/matplotlib/backends/web_backend/js/nbagg_mpl.js
index 9881819de855..0f538979d19d 100644
--- a/lib/matplotlib/backends/web_backend/js/nbagg_mpl.js
+++ b/lib/matplotlib/backends/web_backend/js/nbagg_mpl.js
@@ -48,11 +48,19 @@ mpl.mpl_figure_comm = function (comm, msg) {
         console.error('Failed to find cell for figure', id, fig);
         return;
     }
+    fig.cell_info[0].output_area.element.one(
+        'cleared',
+        { fig: fig },
+        fig._remove_fig_handler
+    );
 };
 
 mpl.figure.prototype.handle_close = function (fig, msg) {
     var width = fig.canvas.width / fig.ratio;
-    fig.root.removeEventListener('remove', this._remove_fig_handler);
+    fig.cell_info[0].output_area.element.off(
+        'cleared',
+        fig._remove_fig_handler
+    );
 
     // Update the output cell to use the data from the current canvas.
     fig.push_to_output();
@@ -171,13 +179,13 @@ mpl.figure.prototype._init_toolbar = function () {
     titlebar.insertBefore(buttongrp, titlebar.firstChild);
 };
 
-mpl.figure.prototype._remove_fig_handler = function () {
-    this.close_ws(this, {});
+mpl.figure.prototype._remove_fig_handler = function (event) {
+    var fig = event.data.fig;
+    fig.close_ws(fig, {});
 };
 
 mpl.figure.prototype._root_extra_style = function (el) {
     el.style.boxSizing = 'content-box'; // override notebook setting of border-box.
-    el.addEventListener('remove', this._remove_fig_handler);
 };
 
 mpl.figure.prototype._canvas_extra_style = function (el) {

From 75da6c8c403984bf99d180ac8d6e2e8f25da9261 Mon Sep 17 00:00:00 2001
From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
Date: Fri, 11 Sep 2020 19:52:35 -0400
Subject: [PATCH 2/2] CI: Pin nbconvert to working version.

---
 requirements/testing/travis_extra.txt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/requirements/testing/travis_extra.txt b/requirements/testing/travis_extra.txt
index 19b774b382f7..0b18fc58394a 100644
--- a/requirements/testing/travis_extra.txt
+++ b/requirements/testing/travis_extra.txt
@@ -1,7 +1,7 @@
 # Extra pip requirements for the travis python 3.7+ builds
 
 ipykernel
-nbconvert[execute]
+nbconvert[execute]!=6.0.0,!=6.0.1
 nbformat!=5.0.0,!=5.0.1
 pandas!=0.25.0
 pikepdf