I have noticed this issue with TextFields, but it probably also relates to other classes as well. Changing the field from editable to non-editable also changes it from selectable to not selectable. There are many situations in which you might want to be able to select content, but not have it be editable.
The code bringing this change appears to be TextPainter#paintTextAdapterTextSel(Painter, TextAdapter), specifically line 165. While I can also imagine that there are situations where you might not want to have the information be selectable either, I think it would be better to have the defaults still retain selectability, with the functionality able to be turned off if such is required for descendant purposes.
I have noticed this issue with TextFields, but it probably also relates to other classes as well. Changing the field from editable to non-editable also changes it from selectable to not selectable. There are many situations in which you might want to be able to select content, but not have it be editable.
The code bringing this change appears to be
TextPainter#paintTextAdapterTextSel(Painter, TextAdapter), specifically line 165. While I can also imagine that there are situations where you might not want to have the information be selectable either, I think it would be better to have the defaults still retain selectability, with the functionality able to be turned off if such is required for descendant purposes.