I'm using Kitchen sink example to explore ST API and i have a little problem.
I want to replace the backButton of the navigation panel with an icon (reply) with no borders (mask plain).

The backButton of the navigation panel is describe like this :
Code:
this.backButton = new Ext.Button({
    text: this.backText,
    ui: 'back',
    handler: this.onUiBack,
    hidden: true,
    scope: this
});
I change it like this :
Code:
this.backButton = new Ext.Button({
    iconCls: 'reply',
    iconMask: true,
    ui: 'plain',
    handler: this.onUiBack,
    hidden: true,
    scope: this
});
it works on iPhone but not when i 'm on Chrome/PC
so after :
Code:
this.navigationPanel = new Ext.NestedList({
    store: sink.StructureStore,
    useToolbar: Ext.is.Phone ? false : true,
    updateTitleText: false,
    dock: 'left',
    hidden: !Ext.is.Phone && Ext.orientation == 'portrait',
    toolbar: Ext.is.Phone ? this.navigationBar : null,
    listeners: {
        itemtap: this.onNavPanelItemTap,
        scope: this
    }
});
i add :
Code:
this.navigationPanel.backButton.setText(null);
this.navigationPanel.backButton.iconCls = 'reply';
this.navigationPanel.backButton.iconMask = true,
this.navigationPanel.backButton.ui = 'plain';
and i have my icon on Chrome/PC but also still appearing a 'back' text before the icon and i don't know what to do.

thanks