I used UITextField.getCursorPosition().jumpToEnd() to jumpt to the end of the text, but it doesn't work correctly after resizing the UITextField.

I'm not sure what you mean with the jumpToEnd().
But if you mean that the charOffset doesn't automatically go back so that the full width is used instead of leaving some blank, I don't really see that as an issue. And I'm not sure it's worth fixing.

See the screenshot when decreasing size.. It cuts off the end of the string instead of still showing the end.

Well yes, when you resize, the offset stays the same. Like I said, not really an issue.

I guess not many people are going to actually resize the window there. I still consider it an issue but if it works as it should work...

The question is, when you decrease the size, why should the end offset be constant instead of the start offset ? Is it because the end offset happens to match string length ?

Because that's where I set the cursor position and after resize the cursor position is no longer in the visible area.

That's because when you resize, you loose the focus of the textfield and there is no cursor anymore.

I set the cursor position to the end of the string right after setting the string to match vanilla behavior in this case. Setting it seems to work even when that component is not in focus. So it still has a cursor position even if the cursor is not shown.