tor-browser

commit 3d4d2f96a0c489728e59a5e9d9a629f4ce0baaed
parent 6d91498cf88ec45d892676ef7a6f155b3661f1a8
Author: DJ <dj@walker.dev>
Date:   Wed,  7 Jan 2026 20:58:04 +0000

Bug 2007838 - dismiss tab preview at beginning of tab drag. r=tabbrowser-reviewers,sthompson

Differential Revision: https://phabricator.services.mozilla.com/D277879

Diffstat:
M
browser/components/tabbrowser/content/tab-hover-preview.mjs
 | 
11
+++++++++++
M
browser/components/tabbrowser/test/browser/tabs/browser_tab_preview.js
 | 
75
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 86 insertions(+), 0 deletions(-)
diff --git a/browser/components/tabbrowser/content/tab-hover-preview.mjs b/browser/components/tabbrowser/content/tab-hover-preview.mjs
@@ -83,6 +83,16 @@ export default class TabHoverPanelSet {
     );
 
     this.#setExternalPopupListeners();
+    this.#win.gBrowser.tabContainer.addEventListener("dragstart", event => {
+      const target = event.target.closest?.("tab, .tab-group-label");
+      if (
+        target &&
+        (this.#win.gBrowser.isTab(target) ||
+          this.#win.gBrowser.isTabGroupLabel(target))
+      ) {
+        this.deactivate(null, { force: true });
+      }
+    });
   }
 
   /**
@@ -191,6 +201,7 @@ export default class TabHoverPanelSet {
     return (
       // All other popups are closed.
       !this.#openPopups.size &&
+      !this.#win.gBrowser.tabContainer.hasAttribute("movingtab") &&
       // TODO (bug 1899556): for now disable in background windows, as there are
       // issues with windows ordering on Linux (bug 1897475), plus intermittent
       // persistence of previews after session restore (bug 1888148).
diff --git a/browser/components/tabbrowser/test/browser/tabs/browser_tab_preview.js b/browser/components/tabbrowser/test/browser/tabs/browser_tab_preview.js
@@ -1292,6 +1292,81 @@ add_task(async function testDragToCancelPreview() {
   await SpecialPowers.popPrefEnv();
 });
 
+add_task(async function tabPreviewHidesWhenDraggingOverPanel() {
+  const tab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "about:robots"
+  );
+  const previewElement = document.getElementById(TAB_PREVIEW_PANEL_ID);
+
+  await openTabPreview(tab);
+
+  const previewHidden = BrowserTestUtils.waitForPopupEvent(
+    previewElement,
+    "hidden"
+  );
+  const dragend = BrowserTestUtils.waitForEvent(tab, "dragend");
+
+  EventUtils.synthesizePlainDragAndDrop({
+    srcElement: tab,
+    destElement: null,
+    stepX: 10,
+    stepY: 0,
+  });
+
+  await previewHidden;
+  Assert.equal(
+    previewElement.state,
+    "closed",
+    "Preview closes when dragging downward over the panel"
+  );
+
+  await dragend;
+
+  BrowserTestUtils.removeTab(tab);
+  await resetState();
+
+  const groupTab = await BrowserTestUtils.openNewForegroundTab(
+    gBrowser,
+    "about:robots"
+  );
+  const group = gBrowser.addTabGroup([groupTab]);
+  group.collapsed = true;
+
+  await openGroupPreview(group);
+
+  const groupPreviewElement = document.getElementById(
+    TAB_GROUP_PREVIEW_PANEL_ID
+  );
+  const groupPreviewHidden = BrowserTestUtils.waitForPopupEvent(
+    groupPreviewElement,
+    "hidden"
+  );
+  const groupDragend = BrowserTestUtils.waitForEvent(
+    group.labelElement,
+    "dragend"
+  );
+
+  EventUtils.synthesizePlainDragAndDrop({
+    srcElement: group.labelElement,
+    destElement: null,
+    stepX: 10,
+    stepY: 0,
+  });
+
+  await groupPreviewHidden;
+  Assert.equal(
+    groupPreviewElement.state,
+    "closed",
+    "Group preview closes when dragging downward over the panel"
+  );
+
+  await groupDragend;
+
+  BrowserTestUtils.removeTab(groupTab);
+  await resetState();
+});
+
 /**
  * Other open panels should prevent tab preview from opening
  */