In previous releases when attribute autosize == true attributes from $SUBJECT were ignored. In 4.3.7., they are not. When used together (does not really make sense IMHO, but maybe I am neglecting some use case), the popup width is not adjusted automatically.
Note that the above was original issue, which as you can see in the comments we identified as a correct change of behavior. In the comments below you can also find other issues which emerged when fixing