From 707aba1b0b799aad3abcb3af5968c4a5e1025208 Mon Sep 17 00:00:00 2001
From: Neil Deakin <neil@mozilla.com>
Date: Mon, 10 Aug 2020 09:47:38 +0000
Subject: [PATCH] Bug 1644337, add an isAnchored property to popups, as popups
 can be anchored to a rectangle as well as a node. This prevented the arrow
 from appearing in panels, r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D86099
---
 dom/webidl/XULPopupElement.webidl | 6 ++++++
 dom/xul/XULPopupElement.cpp       | 9 +++++++++
 dom/xul/XULPopupElement.h         | 2 ++
 toolkit/content/widgets/panel.js  | 9 ++-------
 4 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/dom/webidl/XULPopupElement.webidl b/dom/webidl/XULPopupElement.webidl
index 9396844ee33d..7c479f6030e5 100644
--- a/dom/webidl/XULPopupElement.webidl
+++ b/dom/webidl/XULPopupElement.webidl
@@ -142,6 +142,12 @@ interface XULPopupElement : XULElement
    */
   readonly attribute Node? triggerNode;
 
+  /**
+   * True if the popup is anchored to a point or rectangle. False if it
+   * appears at a fixed screen coordinate.
+   */
+  readonly attribute boolean isAnchored;
+
   /**
    * Retrieve the anchor that was specified to openPopup or for menupopups in a
    * menu, the parent menu.
diff --git a/dom/xul/XULPopupElement.cpp b/dom/xul/XULPopupElement.cpp
index e4ac24e24ce0..5bdf66f39f66 100644
--- a/dom/xul/XULPopupElement.cpp
+++ b/dom/xul/XULPopupElement.cpp
@@ -188,6 +188,15 @@ nsINode* XULPopupElement::GetTriggerNode() const {
   return nsMenuPopupFrame::GetTriggerContent(menuPopupFrame);
 }
 
+bool XULPopupElement::IsAnchored() const {
+  nsMenuPopupFrame* menuPopupFrame = do_QueryFrame(GetPrimaryFrame());
+  if (!menuPopupFrame) {
+    return false;
+  }
+
+  return menuPopupFrame->IsAnchored();
+}
+
 // FIXME(emilio): should probably be renamed to GetAnchorElement?
 Element* XULPopupElement::GetAnchorNode() const {
   nsMenuPopupFrame* menuPopupFrame = do_QueryFrame(GetPrimaryFrame());
diff --git a/dom/xul/XULPopupElement.h b/dom/xul/XULPopupElement.h
index 0ce18a063781..b7703a471e96 100644
--- a/dom/xul/XULPopupElement.h
+++ b/dom/xul/XULPopupElement.h
@@ -72,6 +72,8 @@ class XULPopupElement : public nsXULElement {
 
   nsINode* GetTriggerNode() const;
 
+  bool IsAnchored() const;
+
   Element* GetAnchorNode() const;
 
   already_AddRefed<DOMRect> GetOuterScreenRect();
diff --git a/toolkit/content/widgets/panel.js b/toolkit/content/widgets/panel.js
index f462a2081aef..44d56bde7c7a 100644
--- a/toolkit/content/widgets/panel.js
+++ b/toolkit/content/widgets/panel.js
@@ -96,12 +96,7 @@
     }
 
     adjustArrowPosition() {
-      if (!this.isArrowPanel) {
-        return;
-      }
-
-      var anchor = this.anchorNode;
-      if (!anchor) {
+      if (!this.isArrowPanel || !this.isAnchored) {
         return;
       }
 
@@ -159,7 +154,7 @@
     on_popupshowing(event) {
       if (this.isArrowPanel && event.target == this) {
         var arrow = this.shadowRoot.querySelector(".panel-arrow");
-        arrow.hidden = this.anchorNode == null;
+        arrow.hidden = !this.isAnchored;
         this.shadowRoot
           .querySelector(".panel-arrowbox")
           .style.removeProperty("transform");