(Cards on the table: I say the following as someone who thinks that retweets are one of the biggest useless annoyances on Twitter.)
1) This change/addition would be great IFF retweets were then NOT part of replies/mentions. I've got a script that checks for mentions and then emails me them, and RTs are just clutter. 2) I would MUCH RATHER see something done about being able to follow a conversation, i.e. I give you a status ID, and you show me all the messages related to it (all the messages in the 'conversation chain' before or after it. This has been a long-standing wish causing many people to try to create their own hackish workarounds because really it has to be supported in the API. 3) It would be nice if someone RTs a message and someone 'favorites' it, the favorite goes to the original author. OTOH then we get into "Well is this a 'value added' RT?" and then "Does 'HAHAHA THIS MADE ME LAFF' count as 'value'?" but at least for "straight" RTs, it would at least bring some value to having this in the API. I realize that not everyone will benefit from every API change, but focusing on something like RTs (which definitely have lots of fans and lots of detractors) instead of conversation threads (which people have been requesting for longer than RTs have even been 'a thing' and which I've never heard anyone be against and can't imagine what an argument against would even look like) is confusing to me. My 2ยข TjL
