Hybrid Keysignature
This in fact is an extension to the microtones topic. It would really a great help for us middle-eastern composers if we can customise the key signature into something like, for example: B flat & E half-flat (actually a very much used one), or even worse: B natural & E half-flat and A flat (another one that is fairly recurrent).
On many other graphical notation editors a trick can be done: write a normal flat, then a tremolo stroke, then move the latter over the flat's stem. But with MuseScore this is just not possible, since, just like LilyPond, it doesn't use the tremolo mark as a separate glyph, or so it seems.
Comments
You are correct that this is not supported. However you can cheat if all you want is the correct look and you don't care if it exports correctly.
From the main menu choose Create > Symbols. Look for the symbols that you want in your signature (such as flat, half flat, etc). First you will need to drag them to a note. Once the symbol is attached to a note you can adjust drag it to the start of the staff so that it looks like a key signature.
This procedure is probably too tedious if you want a key signature on every line, or you are making many scores, and it is of course not officially supported. I just thought I'd share as a proof of concept.
In reply to You are correct that this is by David Bolton
A key signature must have width proportional to the number of accidental it contains. Can one drag the time signature to make room for added signs?! What about start of the second, and later systems? Could the first note in the first measure in each system be horizontally adjusted in an acceptable manner??
No, no, no. I suppose one can only wait for anything to transpire...
HosAdeeb