有一个属性来测试这个，而不是比较实际的资源颜色.

There is a property to test for this, rather that comparing the actual resource color.

Visibility v = (Visibility)Resources["PhoneLightThemeVisibility"]; 

if (v == System.Windows.Visibility.Visible)
{
    // Is light theme
}
else
{
    // Is dark theme
}