Queries whether a specified character is a half-width or full-width character. You can send this message explicitly or use the Editor_IsCharHalfOrFull inline function.
wParam = (WPARAM)(WCHAR)ch;
lParam = (LPARAM)0;
Specifies the character code by Unicode to be queried.
If the character is a full-width character, the return value is two. If the character is a half-width character, the return value is one.