Add <Insert> keyboard shortcut to create a new FX channel

[Wallacoloo]

This implements a keyboard shortcut from #1488 for quickly creating a new mixer channel.

The discussion wasn't clear as to where the channel should be inserted (e.g. to the right of the current channel or to the right of the rightmost channel). So I decided upon having the Insert shortcut mimic the behavior of the "+" button for consistency & ease of implementation.

I tested this change by making some channels, connecting them to a source and swapping them around; seemed to work as expected.

[tresf]

@Sti2nd we need to assign a valid shortcut to this. I don't know if insert is good or not.

[Wallacoloo]

This really should have been settled in #1488, but I guess that shows the downside to megathreads in that some things get missed.

I think either ctrl+insert or shift+insert would make sense, but they are both awkward to press. Another option is something using the + key. Unfortunately, both ctrl+plus and ctrl+shift+plus are both commonly associated with zooming in.

One of the suggestions in the megathread was that insert+<number> should insert <number> new FX channels. While I personally don't see much use in adding 9 FX channels simultaneously, ctrl+1 seems like an intuitive way to add 1 new channel (and it could be extended to ctrl+2, ctrl+3, ... if desired).

Another possibility is ctrl+i. This again requires both hands, but is less awkward than ctrl+insert.

Currently, my vote goes towards implementing ctrl+1 (and only ctrl+1 - no higher numbers). But I don't know if this might have potential future conflicts.

[tresf]

Right now, we use CTRL + Insert (or possibly CTRL + Shift + insert) to add new bars to the Song Editor. Perhaps that should be carried over?

[Wallacoloo]

@tresf (edited because I initially misunderstood what shift+insert did) Shift+Insert in the song editor appears to insert an empty bar to the right of the playhead. I suppose inserting a new FX channel is a similar action, so Shift+insert might indeed be the right shortcut to use here.

[tresf]

@Wallacoloo I guess I'm having a hard time with this one... CTRL + N is the closest I can think of, but that's already used for New Project. :\

That's why I'm hoping for some feedback from others. :)

@Sti2nd @Umcaruje @mikobuntu @unfa opinions? :)

[Wallacoloo]

@tresf in case you read my comment through email, I immediately edited my previous comment pretty heavily because I was wrong about what shift+insert did in the song editor. I think shift+insert may be the best option mentioned so far.

[tresf]

@Wallacoloo let's march forward with that then. We may decide to change it down the road, but that way we can have something, and it can be fairly consistent. 👍

[Wallacoloo]

@tresf switched to shift+insert. Tested & it works as expected.

[tresf]

👍

[tresf]

@Sti2nd please add to the chart. :)

[Sti2nd]

Yup!

[miketurn]

Sorry to ask this question but does this post mean that the "Shift + Insert" key has been implented into LMMS to insert the track or does it mean that the hotkey has been reserved for a future adding of this feature?
I am using version 1.1.3 (32Bit) and this hotkey does not work for me when testing it out in the mixer.
Thank You

[tresf]

This is the code commit, adding the feature as described (1.2). The other conversation is in regards to documentation.