For accordion: Insert a register toolbar

You can already compose your own register symbol.

1. Open the symbol palette
2. Drag and drop the empty registry symbol you want in the score
3. In the symbol palette, drag a dot to the registry symbol, the symbol should turn red, and drop it
4. Move the dot to the right place in the registry symbol
5. Repeat step 3. and 4. for each dot you need.

I counted 19 possible registers and that's using only the 3 area symbol. I'm not sure it's a good idea to have all of them included by default.
You can copy paste the symbol from this score : http://musescore.com/score/2268

Linked with: http://musescore.org/en/node/3884#comment-30522

"this feature request is basically all about making a custom palette with your own (svg) symbols."

For anyone else searching for accordion switch symbols: MuseScore 2's Master palette has a Symbols category at the end, which contains (after lots of microtonal accidentals) quite a few accordion registrations as single premade icons, in addition to empty register symbols and a combining dot.

They cover all possibilities in a 4-reed LMMH treble section, as well as some musette/LMMMH registrations; and also the seven "standard" Stradella bass registers described in Donald Balestrieri's "Registers of the Standard Stradella Keyboard".

I was glad to see these!

You can create a Custom palette with just the registration symbols you're likely to need. I'll attach the one I created. (You can fix mistakes in tooltip names by right-clicking over a symbol and renaming it in Properties. Also, I left out the round two-space symbols and rectangular three-space symbols that I'm unfamiliar with.)
NOT FOUND: 2

@grinningcat Great work! I made a small video to show how the palette can be loaded.

Click on the image below to start the video:

Would be nice to also have the free bass register switches (with usually only one line) like in the link.

http://lilypond.org/doc/v2.19/Documentation/96/lily-29e6488d.png

Those free bass register symbols (that I wasn't familiar with) are also included under "Symbols" in the master palette. Thanks for pointing them out!

@Tomas and others. This is just what I was looking for.
Thanks.

See https://github.com/musescore/MuseScore/pull/4885

The part with a palette for accordion was merged, so this issue seems to be fixed.

Automatically closed -- issue fixed for 2 weeks with no activity.

We have the Accordion Register Switches but I wanted them to also work cause I love the various Octaves each switch produces. That could be a new upgrade for MuseHub

Then open a new issue and let this here rest in peace