I've experienced this on the listed affected versions.

Here's a video demonstrating the issue: https://gfycat.com/coolboringappaloosa

As you can see, sometimes the cursor for the text falls 1 character behind what is actually being typed. You can still type and the letters will be appended correctly, but the cursor position is confusing.

As an aside, this textbox has got nothing on the Java one for one main reason - the lack of a highlight when selecting text. It's really difficult to tell what you're actually doing in these boxes and it makes them really frustrating to use.