使用NAVIGATION_MODE_LIST时如何更改微调器的颜色？

Question

我似乎无法弄清楚如何让微调器变白：

我需要使用哪种样式才能将其更改为白色？我正在使用ActionBarSherlock。

相关代码：

 public void onCreate(Bundle savedInstanceState) 
 {
    ....
    // Just a class to hold description/value pairs
    DescriptionValuePair[] pastdays = new DescriptionValuePair[] {   
            new DescriptionValuePair("Past 30 days", "30"), 
            new DescriptionValuePair("Past 60 days", "60"), 
            new DescriptionValuePair("Past 90 days", "90"), 
            };
    ArrayAdapter adapter_pastdays = null;

    ActionBar bar=getSupportActionBar();

    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
        adapter_pastdays = new ArrayAdapter(bar.getThemedContext(), R.layout.sherlock_spinner_item, pastdays );
    }
    else {
        adapter_pastdays = new ArrayAdapter(this, R.layout.sherlock_spinner_item, pastdays );
    }

    adapter_pastdays.setDropDownViewResource(R.layout.sherlock_spinner_dropdown_item);
    bar.setNavigationMode(ActionBar.NAVIGATION_MODE_LIST);
    bar.setListNavigationCallbacks(adapter_pastdays, this);
 }