OK, I find the reason of this issue.
This issue also happens in the latest Notepad++.
The problem is that a bold Chinese font is a bit wider than a normal Chinese font.
Under C::B, when the Chinese character is after the
, which means it's a doxygen style comment, it will be bold, and this issue happens. If I set the doxygen comment font style to bold font, this issue also happens under Notepad++.
I'm not sure how I can solve this.