Bug 1557286 - should preventDefault the event after showing an input field contextmenu to avoid other context menus showing. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D33935

--HG--
extra : moz-landing-system : lando

toolkit/content/editMenuOverlay.js

@@ -92,4 +92,7 @@ window.addEventListener("contextmenu", (e) => {
 
   goUpdateGlobalEditMenuItems(true);
   popup.openPopupAtScreen(e.screenX, e.screenY, true);
+  // Don't show any other context menu at the same time. There can be a
+  // context menu from an ancestor too but we only want to show this one.
+  e.preventDefault();
 });

toolkit/content/tests/chrome/file_edit_contextmenu.xul

@@ -23,8 +23,15 @@
   <command id="cmd_switchTextDirection" oncommand="goDoCommand('cmd_switchTextDirection');"/>
 </commandset>
 
+<menupopup id="outer-context-menu">
+  <menuseparator id="customizeMailToolbarMenuSeparator"/>
+  <menuitem id="hello" label="Hello" accesskey="H"/>
+</menupopup>
+
+<hbox context="outer-context-menu">
 <html:textarea />
 <html:input />
 <textbox is="search-textbox"/>
+</hbox>
 
 </window>

toolkit/content/tests/chrome/test_edit_contextmenu.html

@@ -55,6 +55,10 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1513343
       ok(contextmenu, "context menu exists after right click");
       await popupshown;
 
+      // Check that we only got the one context menu, and not two.
+      let outerContextmenu = win.document.getElementById("outer-context-menu");
+      ok(outerContextmenu.state == "closed", "the outer context menu state is is not closed, it's: " + outerContextmenu.state);
+
       ok(!contextmenu.querySelector("[command=cmd_undo]").hasAttribute("disabled"), "undo enabled");
       ok(contextmenu.querySelector("[command=cmd_cut]").hasAttribute("disabled"), "cut disabled");
       ok(contextmenu.querySelector("[command=cmd_copy]").hasAttribute("disabled"), "copy disabled");