DevTools: Remember the last focused widget.

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

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  * 1. Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *
@@ skipping 145 matching lines @@
         this.suspendInvalidations();
         if (this._mainWidget)
             this._mainWidget.detach();
         this._mainWidget = widget;
         if (widget) {
             widget.element.classList.add("insertion-point-main");
             widget.element.classList.remove("insertion-point-sidebar");
             widget.attach(this);
             if (this._showMode === WebInspector.SplitWidget.ShowMode.OnlyMain || this._showMode === WebInspector.SplitWidget.ShowMode.Both)
                 widget.showWidget(this.element);
+            this.setDefaultFocusedChild(widget);
         }
         this.resumeInvalidations();
     },
 
     /**
      * @param {!WebInspector.Widget} widget
      */
     setSidebarWidget: function(widget)
     {
         if (this._sidebarWidget === widget)
@@ skipping 742 matching lines @@
         this._showHideSidebarButton.classList.toggle("toggled-hide", !sidebarHidden);
         this._showHideSidebarButton.classList.toggle("top-sidebar-show-hide-button", !this.isVertical() && !this.isSidebarSecond());
         this._showHideSidebarButton.classList.toggle("right-sidebar-show-hide-button", this.isVertical() && this.isSidebarSecond());
         this._showHideSidebarButton.classList.toggle("bottom-sidebar-show-hide-button", !this.isVertical() && this.isSidebarSecond());
         this._showHideSidebarButton.classList.toggle("left-sidebar-show-hide-button", this.isVertical() && !this.isSidebarSecond());
         this._showHideSidebarButton.title = sidebarHidden ? WebInspector.UIString("Show %s", this._showHideSidebarButtonTitle) : WebInspector.UIString("Hide %s", this._showHideSidebarButtonTitle);
     },
 
     __proto__: WebInspector.Widget.prototype
 }