Sequencer improvements

[enh3]

Hi, first of all I want to thank you for an excellent project. There are several things about OpenMusic (not sure if they're Mac specific) like undo, copy and paste, and scrolling issues that seem to be resolved with OM#, and there are a host of other improvements. One thing that I would love to see improved further is the sequencer. I have a few ideas :

1. Customization of the colours in the sequencer. I like that you've included the two views, and the new sequencer view is a great idea, but I find the design of the maquette in OM (using 7.3 but should be the same in other versions) more visually appealing. The dull gray background is kind of uninspiring, and though I like that the boxes have more information, I wish that when toggling the object with m, that one of the states showed no text at all (not even the . I think the possibility to have a more stripped down version can make the overall structure les cluttered, and clearer as a result. A bonus would be having the option to have the background of an object with music staves on it have the same background as the sequencer like in an OM maquette (maybe just by selecting the same colour as the background for each).
2. Integration of Poly and Multi-seq objects. Maybe this is just on my side, but I can't seem to figure out how to get these objects into the sequencer, in either mode.
3. When dragging an object into the sequencer, at the moment it disappears from its original home. This seems like a bit of a dangerous functionality. I'd rather it leave the object where it is, giving me the option to delete it if I like.
4. This is a strange issue I've been finding that every once in a while (not sure how to reproduce). An object will get stuck underneath another one and then they can't be disconnected.

Let me know if any of these ideas aren't clear. I understand that there are a lot of different development priorities, but I wanted to add my two cents and thank the devs for a great contribution!

Kjel