How to keep the keyboard focus in the Text Box widget when click another widget with mouse?

I created a function to enter the text assigned to that button into the text box widget when I click the button.

By default, you have to click the button with your mouse.
I lose the focus of the text box when I click with the mouse.

When I enter text, I use the ‘Set User Focus’ node to return focus.
I tried Button’s ‘Is Focus’ with ‘False’.

In either case, however, the focus is lost at the point of the mouse press.
There is no problem with English input, but vowels and consonants are broken for Korean input.

Since languages other than English should not lose focus for a moment, I want a text box that never loses focus.

The current problem is that the focus of the text box disappears when the mouse is pressed.
Is there anyone who can tell me how to fix the focus of the text box in any situation?

There’s no point in returning it after it’s lost. The focus itself should not be taken away for a single moment.

The OnRemovedFromFocusPath() function is called when the mouse is pressed, but the OnFocusLost() function is not called.

This is the only information I know.
I need help.