Enable tab scroll in the viewport.

static/plugin_dbui/src/appviewport.js

@@ -74,8 +74,10 @@ App.Viewport = Ext.extend(Ext.Viewport, {
             }, {
                 autoScroll: true,
                 defaults: {layout: 'fit'},
+                enableTabScroll: true,
                 itemId: 'tabPanel',
                 region: 'center',
+                tabPosition: 'top',
                 xtype: 'tabpanel'
             }, {
                 height: 25,