QWebEngineView input cursor be a black box with korean language

I tried to type korean language to html input using QWebEngineView
But i couldn't , and i checked examples about WebEngineWidget
Likewise it doesn't work

above resolved 5.5.1

On the other hand, quicknanobrowser example using qml could type korean with some bug

All example has bugs.
First, once i type korean, cursor be a black box so it blind character.
Second, when cursor be a black, last character is duplicated after click arrow, space key.