Backed out changeset 52b323d94478 (bug 1694926) for test failures in comm/mail/test/browser/tabmail/browser_dragndrop.js. r=backout DONTBUILD

mail/base/content/tabmail-tabs.js

@@ -426,6 +426,10 @@
           return;
         }
 
+        if (!event.originalTarget.classList.contains("tabs-closebutton")) {
+          return;
+        }
+
         let tabbedBrowser = document.getElementById("tabmail");
         if (this.localName == "tab") {
           // The only sequence in which a second click event (i.e. dblclik)
@@ -482,6 +486,12 @@
 
           // Stop propagating for the one-close-button case.
           event.stopPropagation();
+
+          // Prevent default only if the double click happened on the close
+          // button. This is to prevent accidental toggle of full size window.
+          if (event.originalTarget.classList.contains("tabs-closebutton")) {
+            event.preventDefault();
+          }
         },
         true
       );

mail/themes/linux/mail/tabmail.css

@@ -71,6 +71,11 @@ tabpanels {
   }
 }
 
+/* Tabstrip close button */
+.tabs-closebutton {
+  margin-top: 1px;
+}
+
 /**
  * Tab Scrollbox Arrow Buttons
  */

mail/themes/osx/mail/tabmail.css

@@ -93,6 +93,18 @@ tabmail > tabbox > tabpanels {
   appearance: none !important;
 }
 
+/**
+ * Tabstrip close button
+ */
+
+.tabs-closebutton {
+  margin-top: 1px;
+}
+
+.tabs-closebutton:hover > .toolbarbutton-icon {
+  background-image: none !important;
+}
+
 /**
  * Tab Scrollbox Arrow Buttons
  */

mail/themes/windows/mail/tabmail.css

@@ -45,6 +45,19 @@ tabpanels {
   margin-inline-start: 0;
 }
 
+/**
+ * close buttons
+ */
+
+.tabs-closebutton-box > .tabs-closebutton {
+  margin-top: 1px;
+  padding: 0 2px;
+}
+
+.tabs-closebutton:focus {
+  outline: none !important;
+}
+
 /**
  * Tab Scrollbox Arrow Buttons
  */