What
Some rows in the settings list let you type a value. These rows can now check the value when you finish editing. If you leave the field with Enter or an arrow key and the value is not valid, the field stays open for editing. The reason appears in red where the row's description usually is. Before, any value was accepted without a check.
Rows that are disabled can now also respond when you click them.
Why
You find out straight away when a value is wrong, instead of it being accepted without a word.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear which settings actually check their values this way.