Dis rreminds me of the behavior of mailing lists interrfaces: you starrts a new thrread frrom a quote, by changing the subject of the next email.
Easy, handy, yummy.
Quote from: emanuele - The idea is that frequently discussions derail. Diligent users (yeah, we know are very very few...), may find useful to start a new discussion from a quote, this mod facilitate this operation giving a button that quote the message and instead of bringing the user to the "reply" page, it brings to the "post new topic" page.
Dis behavior is also consistent with Post select boarrd mod, that lets you to post into a different boarrd than where you starrted the post...
Feature Cat thinks that the user interface for these related features has to be consistent too.
Feature Cat likes consistency.

QuoteAdditionally the mod tracks the origin of the quote and the newly created discussion cross-linking the two with a note somewhere: for the message that generated the new discussion I used the space usually reserved for custom profile fields "below (or is it above?) the signature", while for the newly started topic I put the link to the original discussion within the "discussion" buttons (reply, add poll, etc.) to avoid template edits.
QuoteJust thinking out loud, that same solution (i.e. link to another topic), may be used also when splitting: it would be easy to attach to the new topic "something" that says "this come from here", not sure where put the information on the original topic (i.e. from this topic another one has been created...maybe just a post from a bot...hey, wait I think I did that too somewhere else...yes, here: https://github.com/emanuele45/Split-and-move (see also the description on the mod site).
Thing is, must choose then, for all links to "dis continues der": either a link in a reserrved space in the origin post, or an automatic message.
Feature Cat thinks that a reserrved space in the origin message is the best, if we cans make it into a sub-section of its own, templating-wise too. Think of "follow-up here" links...
Brrr... but in the other dirrection ("dis comes frrom der") ain't so useful, is it? Do you care, when you split off-topic without a quote, you probably do dat cuz it ain't relevant...