One window, different fonts?

Hi, Too much of the confusion has driving me crazy…
Code:

Result:
[attachment=0]AlertWindow.PNG[/attachment]
Question:
Why the title and content can be displayed correctly, but the button text isn’t correct?

The button will use a different font, and I guess the font doesn’t contain those characters.

My mentor, why not the button to use same font with the title by default? or, how to get the button to use the same font following the title? In this way, the default can display local text, at least less to write a line of code (LookAndFeel::setDefaultSansSerifTypefaceName (…))