I had to learn this today and to be honest it just made my head spin (more than most grammar).
First of all the explanation says
Verb [る] (A) + ともなく (1) + Verb [たら] (2) (A)
(1) ともなしに
(2)Verb + と
So my understanding is that this grammar point is するともなくしたら、 or するともなくすると, so the same verb is repeated twice. But one of the examples seems to contradict this;
話を聞くともなく、先生と黒板の方向をぼーっと見ていた。
It’s not clear to me why 聞く isn’t repeated here when the grammar point says the verb is repeated, and the verb is also repeated in other examples.
At the end it also says ともなく and ともなしに will often be seen in sentences that use たら. This puts emphasis on the specific time that something happened while performing another action absentmindedly. Despite translating this way, the action that precedes ともなく itself will be intentional, but the thing that comes about as a result of performing that action will not be what the doer was aiming to achieve.
So is the たら form only used in this situation?
Honestly I feel like someone needs to explain this whole grammar point to me like I’m 5. TIA