C# combo box text with last character coming to the front

Question

When developing c# winform, there is a symptom that when Korean is entered in the combobox and clicked on another space with the mouse, the last character of the text comes to the front.

only Korean, not English

ex) 마우스 -> 스마우

This symptom always occurs in Win8,10, and sometimes in Win7.
So, referring to the site below, Win8,10 has been resolved.

https://kimcblog.com/2019/02/05/c-winform%EC%97%90%EC%84%9C-%ED%95%9C%EA%B8%80-%EC%9E%85%EB%A0%A5%EC%8B%9C-%ED%95%9C%EA%B8%80-%EB%B0%80%EB%A6%BC-%ED%98%84%EC%83%81-%ED%95%B4%EA%B2%B0-%EB%B0%A9%EB%B2%95/

However, it is not yet resolved in Win7.
Please give me a solution and I'll try it.

Development environment
Tool Ver.: Visual Studio 2013
c# winform
.NET Framework 4.6.1