We need to be able to define a fractional maximum number of lines for a TextField. When using an integer number of lines, and there is a lot of text, the user will only see a few of the lines and may think that there are no more.

On the contrary, if you define, say 5.5 lines, and there are in fact, say, 10 lines, the user immediately notices that there is more text to the bottom. In other words, half-lines are visual cues to the users that they are able to scroll to see the rest.

It's a small change that improves usability. To be consistent, I would make minLines also double, although in terms of usability that one is probably not important.

This is NOT a breaking change, and preserves existing maxLines behavior.

Note: I'm the author of #19105 which was fixed by #27205