Cloning tracks and TCOs between Song Editor and B&B Editor

Nobody has claimed this yet.

Currently Ctrl+dragging a track from either editor to the other will bring its TCOs with it. This can be a problem because the order of TCOs in the B&B editor has no relation to song time, and likewise the order in the Song Editor has no relation to the B&B pattern number.

I'd like to suggest the behaviour be changed so that Ctrl+dragging an instrument between the two editors would work exactly like dragging a preset from the browser; in other words, if dragging onto an existing instrument track, keep its TCOs intact if there are any.

A related issue is that Ctrl+dragging TCOs from the B&B Editor to the Song Editor doesn't always work reliably (which will need some investigation), while the same in the other direction is not at all possible. Automation and Sample TCOs can't be cloned in either direction.

Start by tracing Ctrl-drag handling in the Song Editor and B&B Editor, then compare it with dragging a preset from the browser. Check the existing behavior for instrument, automation, sample, and other TCOs; done means cross-editor cloning follows the requested track and TCO rules and unreliable or unsupported directions are addressed.

Written by the indexing model from the issue text.