Add initial draft note about avoiding mismatch for mixed input use

content/practices/keyboard-interface/keyboard-interface-practice.html

@@ -376,6 +376,16 @@ <h3>Managing Focus in Composites Using <code>aria-activedescendant</code></h3>
             </li>
           </ol>
         </section>
+
+          <div class="note">
+            <h4>Note</h4>
+            <p>This guidance focuses specifically on keyboard interaction. However, authors must of course also consider pointer interactions, such as mouse clicks
+              and touchscreen taps. In the case of components that don't "close" when an element is clicked/tapped,
+              authors should take the same steps to set the correct <code>tabindex</code> or <code>aria-activedescendant</code> for the element,
+              in the same way that they would for keyboard navigation. Otherwise, this could lead to a confusing experience for users that switch between pointer
+              and keyboard navigation, as it will lead to a mismatch.</p>
+          </div>
+
       </section>
 
       <section id="kbd_disabled_controls">