Implement built-in support for the Sogou Pinyin Input Method Editor.

Sogou Pinyin is the most popular IME in China (above 80% of the users are using it).

Currently RadRichTextBox doesn't support Sogou Pinyin IME out of the box, and the users have to manually implement it, as described in the "How to implement your own IME support?" (
https://docs.telerik.com/devtools/wpf/controls/radrichtextbox/ime-support#how-to-implement-your-own-ime-support ) help article and the CustomCaret (https://github.com/telerik/xaml-sdk/tree/master/RichTextBox/CustomCaret ) SDK example.