tor-browser

commit eaec21428869c7fbab2ce135ca2c83605e058a08
parent 27e17af20670fe47d0b34083b6819017ae25cac7
Author: Mark Striemer <mstriemer@mozilla.com>
Date:   Thu, 27 Nov 2025 23:46:48 +0000

Bug 2001746 - Don't throw in moz-box-group on keypresses without a valid focus target r=akulyk

Differential Revision: https://phabricator.services.mozilla.com/D273692

Diffstat:
M
toolkit/content/tests/widgets/test_moz_box_group.html
 | 
51
+++++++++++++++++++++++++++++++++++++++++++++++++++
M
toolkit/content/widgets/moz-box-group/moz-box-group.mjs
 | 
12
++++++++----

2 files changed, 59 insertions(+), 4 deletions(-)
diff --git a/toolkit/content/tests/widgets/test_moz_box_group.html b/toolkit/content/tests/widgets/test_moz_box_group.html
@@ -542,6 +542,57 @@
         await SpecialPowers.popPrefEnv();
       });
 
+      add_task(async function testMozBoxGroupKeydownOnWhitespace() {
+        // Test bug 2001746 - ignore keypresses that fire on the ul if whitespace
+        // was clicked in moz-box-group
+        let listTemplate = html`<moz-box-group type="list">
+          <moz-box-item label="item 1"></moz-box-item>
+          <moz-box-item label="item 2"></moz-box-item>
+          <moz-box-item label="item 3"></moz-box-item>
+        </moz-box-group>`;
+        let {
+          children: [boxGroup],
+        } = await testHelpers.renderTemplate(listTemplate);
+
+        let list = boxGroup.shadowRoot.querySelector("ul");
+        ok(list, "Box group has a list element.");
+
+        // Simulate clicking on the list container (whitespace) by focusing it
+        list.focus();
+        is(
+          boxGroup.shadowRoot.activeElement,
+          list,
+          "The list container can be focused."
+        );
+        is(
+          document.activeElement,
+          boxGroup,
+          "The moz-box-group is the activeElement."
+        );
+
+        // Press arrow keys - this should not throw an error
+        let errorThrown = false;
+        try {
+          synthesizeKey("KEY_ArrowDown");
+          await boxGroup.updateComplete;
+          synthesizeKey("KEY_ArrowUp");
+          await boxGroup.updateComplete;
+        } catch (e) {
+          errorThrown = true;
+          ok(false, `Unexpected error: ${e.message}`);
+        }
+
+        ok(
+          !errorThrown,
+          "No error thrown when pressing keys on whitespace in moz-box-group."
+        );
+        is(
+          document.activeElement,
+          boxGroup,
+          "Focus did not move after arrow key press."
+        );
+      });
+
       add_task(async function testMozBoxGroupReorderable() {
         let reorderableTemplate = html`<moz-box-group type="reorderable-list">
           <moz-box-item label="item 1"></moz-box-item>
diff --git a/toolkit/content/widgets/moz-box-group/moz-box-group.mjs b/toolkit/content/widgets/moz-box-group/moz-box-group.mjs
@@ -121,10 +121,14 @@ export default class MozBoxGroup extends MozLitElement {
       }
     }
 
-    let positionAttr =
-      event.target.getAttribute("position") ??
-      // handles the case where an interactive element is nested in a moz-box-item
-      event.target.closest("[position]").getAttribute("position");
+    let positionElement = event.target.closest("[position]");
+    if (!positionElement) {
+      // If the user has clicked on the MozBoxGroup it may get keydown events
+      // even if there is no focused element within it. Then the event target
+      // will be the <ul> and we won't find an element with [position].
+      return;
+    }
+    let positionAttr = positionElement.getAttribute("position");
     let currentPosition = parseInt(positionAttr);
 
     switch (event.key) {