private static FontFamily GetDefaultFontFamily()
Tries common sans-serif fonts first, then Chinese-supporting fonts, finally falls back to first available system font 首先尝试常见无衬线字体,然后尝试支持中文的字体, 最后回退到首个可用系统字体
Throws no exceptions - always returns a font (possibly Arial) 不会抛出异常 - 总是返回一个字体(可能是Arial)