fix(Toolbox): Fix toolbox display when accessing it via keyboard

react/features/toolbox/components/web/Toolbox.js

 import {
     setFullScreen,
     setOverflowMenuVisible,
-    setToolbarHovered
+    setToolbarHovered,
+    setToolboxVisible
 } from '../../actions';
 import { isToolboxVisible } from '../../functions';
 import DownloadButton from '../DownloadButton';
         this._onMouseOver = this._onMouseOver.bind(this);
         this._onResize = this._onResize.bind(this);
         this._onSetOverflowVisible = this._onSetOverflowVisible.bind(this);
+        this._onTabIn = this._onTabIn.bind(this);
 
         this._onShortcutToggleChat = this._onShortcutToggleChat.bind(this);
         this._onShortcutToggleFullScreen = this._onShortcutToggleFullScreen.bind(this);
             <div
                 className = { rootClassNames }
                 id = 'new-toolbox'
+                onFocus = { this._onTabIn }
                 onMouseOut = { this._onMouseOut }
                 onMouseOver = { this._onMouseOver }>
                 <div className = 'toolbox-background' />
         this._doToggleScreenshare();
     }
 
+    _onTabIn: () => void;
+
+    /**
+     * Toggle the toolbar visibility when tabbing into it.
+     *
+     * @returns {void}
+     */
+    _onTabIn() {
+        if (!this.props._visible) {
+            this.props.dispatch(setToolboxVisible(true));
+        }
+    }
+
     _onToolbarOpenFeedback: () => void;
 
     /**