From cf496e47277b250938249549de876e19bc03d202 Mon Sep 17 00:00:00 2001
From: Sean Feng <sefeng@mozilla.com>
Date: Mon, 17 Aug 2020 15:41:19 +0000
Subject: [PATCH] style: Make the document blocked by the topmost element in
 the top layer.

Spec: https://html.spec.whatwg.org/multipage/#blocked-by-a-modal-dialog

Depends on D86392

Differential Revision: https://phabricator.services.mozilla.com/D86227
---
 components/style/element_state.rs                  | 2 ++
 components/style/gecko/non_ts_pseudo_class_list.rs | 1 +
 components/style/gecko/wrapper.rs                  | 1 +
 components/style/style_adjuster.rs                 | 3 +++
 4 files changed, 7 insertions(+)

diff --git a/components/style/element_state.rs b/components/style/element_state.rs
index da44186b44b..a3d001a2fab 100644
--- a/components/style/element_state.rs
+++ b/components/style/element_state.rs
@@ -148,6 +148,8 @@ bitflags! {
 
         /// https://html.spec.whatwg.org/multipage/interaction.html#inert-subtrees
         const IN_MOZINERT_STATE = 1 << 54;
+        /// State for the topmost dialog element in top layer
+        const IN_TOPMOST_MODAL_DIALOG_STATE = 1 << 55;
     }
 }
 
diff --git a/components/style/gecko/non_ts_pseudo_class_list.rs b/components/style/gecko/non_ts_pseudo_class_list.rs
index bdd994c7095..fedbed331f0 100644
--- a/components/style/gecko/non_ts_pseudo_class_list.rs
+++ b/components/style/gecko/non_ts_pseudo_class_list.rs
@@ -53,6 +53,7 @@ macro_rules! apply_non_ts_list {
                 ("-moz-styleeditor-transitioning", MozStyleeditorTransitioning, IN_STYLEEDITOR_TRANSITIONING_STATE, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS),
                 ("fullscreen", Fullscreen, IN_FULLSCREEN_STATE, _),
                 ("-moz-modal-dialog", MozModalDialog, IN_MODAL_DIALOG_STATE, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS),
+                ("-moz-topmost-modal-dialog", MozTopmostModalDialog, IN_TOPMOST_MODAL_DIALOG_STATE, PSEUDO_CLASS_ENABLED_IN_UA_SHEETS),
                 // TODO(emilio): This is inconsistently named (the capital R).
                 ("-moz-focusring", MozFocusRing, IN_FOCUSRING_STATE, _),
                 ("-moz-broken", MozBroken, IN_BROKEN_STATE, _),
diff --git a/components/style/gecko/wrapper.rs b/components/style/gecko/wrapper.rs
index 3d4f186fcc3..ef6ce3df4f3 100644
--- a/components/style/gecko/wrapper.rs
+++ b/components/style/gecko/wrapper.rs
@@ -2063,6 +2063,7 @@ impl<'le> ::selectors::Element for GeckoElement<'le> {
             NonTSPseudoClass::MozDirAttrLikeAuto |
             NonTSPseudoClass::MozAutofill |
             NonTSPseudoClass::MozModalDialog |
+            NonTSPseudoClass::MozTopmostModalDialog |
             NonTSPseudoClass::Active |
             NonTSPseudoClass::Hover |
             NonTSPseudoClass::MozAutofillPreview => {
diff --git a/components/style/style_adjuster.rs b/components/style/style_adjuster.rs
index a23f97d578a..db950397c37 100644
--- a/components/style/style_adjuster.rs
+++ b/components/style/style_adjuster.rs
@@ -163,6 +163,9 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
     ///        pointer-events: none;
     ///        cursor: default;
     ///
+    /// NOTE: dialog:-moz-topmost-modal-dialog is used to override above
+    /// rules to remove the inertness for the topmost modal dialog.
+    ///
     /// NOTE: If this or the pointer-events tweak is removed, then
     /// minimal-xul.css and the scrollbar style caching need to be tweaked.
     fn adjust_for_inert(&mut self) {