DevTools: remove selections on dropdown menu open

third_party/WebKit/Source/devtools/front_end/ui/DropDownMenu.js

Index: third_party/WebKit/Source/devtools/front_end/ui/DropDownMenu.js
diff --git a/third_party/WebKit/Source/devtools/front_end/ui/DropDownMenu.js b/third_party/WebKit/Source/devtools/front_end/ui/DropDownMenu.js
index 9ee2469e8601c1b175b72bf0f47124dc95cc8f26..f9a464d03fe710a2d58dc0766bc7e7c7cff714c7 100644
--- a/third_party/WebKit/Source/devtools/front_end/ui/DropDownMenu.js
+++ b/third_party/WebKit/Source/devtools/front_end/ui/DropDownMenu.js
@@ -22,6 +22,11 @@ UI.DropDownMenu = class extends Common.Object {
   _onMouseDown(event) {
     if (event.which !== 1)
       return;
+
+    // Remove any selections to avoid native context menu items, for example 'Copy'.
+    var selection = UI.inspectorView.element.window().getSelection();

[lushnikov, 2017/03/03 04:11:00]

it would be nice if we can create context menus without this system subitems.

Let's try to improve our context menus!

+    selection.removeAllRanges();
+
     var menu = new UI.ContextMenu(event);
     for (var item of this._items)
       menu.appendCheckboxItem(item.title, this._itemHandler.bind(this, item.id), item.id === this._selectedItemId);