Add ability to change axis tick formats on subchart

Please check this screenshot: http://snag.gy/h8PRk.jpg
As you may see, we have a date and time both in the main and in the sub charts. But in my case it makes no sense showing the time in the subchart. However, showing the time in the main chart still makes sense. Is it possible to have different formats for the subchart and for the main chart? If not yet, then can we have it in future?
Thanks.