diff --git a/source b/source
index c56d43c7b1e..e9030e7394e 100644
--- a/source
+++ b/source
@@ -1828,6 +1828,10 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
    <li><p>If <var>removedNode</var>'s <code data-x="attr-popover">popover</code> attribute is not in
    the <span data-x="attr-popover-none-state">no popover state</span>, then run the <span>hide
    popover algorithm</span> given <var>removedNode</var>, false, false, and false.</p></li>
+
+   <li><p>If <var>removedNode</var> is a <span data-x="concept-button">button</span>, then run
+   <span>check and possibly close popover stack</span> given <var>removedNode</var>'s <span>node
+   document</span>.</p></li>
   </ol>
 
   <p>A <dfn id="insert-an-element-into-a-document" data-x="node is inserted into a document"
@@ -47024,6 +47028,9 @@ interface <dfn interface>HTMLInputElement</dfn> : <span>HTMLElement</span> {
    element's <span data-x="concept-textarea/input-cursor">text entry cursor position</span> to the
    beginning of the text control, and <span data-x="set the selection direction">set its selection
    direction</span> to "<code data-x="">none</code>".</p></li>
+
+   <li><p>Run <span>check and possibly close popover stack</span> given the element's <span>node
+   document</span>.</p></li>
   </ol>
 
   </div>
@@ -81861,6 +81868,11 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
   <ol>
    <li><p>If <var>namespace</var> is not null, then return.</p></li>
 
+   <li><p>If <var>localName</var> is <code data-x="attr-fe-disabled">disabled</code>, <code
+   data-x="attr-fae-form">form</code>, or <code data-x="attr-popovertarget">popovertarget</code>,
+   then run <span>check and possibly close popover stack</span> given <var>element</var>'s
+   <span>node document</span>.</p></li>
+
    <li><p>If <var>localName</var> is not <code data-x="attr-popover">popover</code>, then
    return.</p></li>
 
@@ -82411,6 +82423,42 @@ dictionary <dfn dictionary>DragEventInit</dfn> : <span>MouseEventInit</span> {
    <li><p>Return true.</p></li>
   </ol>
 
+  <p>To <dfn>check and possibly close popover stack</dfn> for a <code>Document</code>
+  <var>document</var>:</p>
+
+  <ol>
+   <li><p>Let <var>stack</var> be <var>document</var>'s <span>auto popover list</span>.</p></li>
+
+   <li><p>Let <var>index</var> <var>stack</var>'s <span data-x="list size">size</span> - 1.</p></li>
+
+   <li>
+    <p><span>While</span> <var>index</var> is greater than 0:</p>
+
+    <ol>
+     <li>
+      <p>If the result of running <span>topmost popover ancestor</span> given
+      <var>stack</var>[<var>index</var>] is not <var>stack</var>[<var>index</var> - 1], then:</p>
+
+      <ol>
+       <li><p>Run <span>hide all popovers</span> given <var>document</var>.</p></li>
+
+       <li><p>Return.</p></li>
+      </ol>
+     </li>
+
+     <li><p>Set <var>index</var> to <var>index</var> - 1.</p></li>
+    </ol>
+   </li>
+  </ol>
+
+  <div class="note">
+   <p><span>Check and possibly close popover stack</span> is used to close multiple popovers which
+   are only open due to their ancestral relationship to each other in the case where that ancestral
+   relationship has been broken. <span>Show popover</span> also closes popovers which don't meet
+   this ancestral relationship by calling <span data-x="hide-all-popovers-until">hide all popovers
+   until</span>.</p>
+  </div>
+
   <h4>The popover target attributes</h4>
 
   <p><span data-x="concept-button">Buttons</span> may have the following content attributes:</p>