Certain alphabets containing symbols that do not have a public Unicode value need to be used with a particular font (e.g. Semantic Alphabet only works if the Semant37 font is used).

I know it's ugly in comparison to the Unicode way of life, but it would be nice if alphabet files could specify preferred fonts, which, if present, would override the font settings in Dasher while that alphabet is being used.

I have thought a bit about the UI for this feature. It's quite hard to do, as the user should be able to insist on choosing the font (overriding the alphabet) if they wish; the font should be returned to the previous setting when a normal alphabet is selected; and it should be clear to the user that the font is being overridden if they start poking around with font settings.  The best I can come up with is as follows:
 
When an alphabet which specifies one or more fonts is selected: If none of the fonts are present, then warn user and continue with current font. Otherwise, store Dasher's current font settings, and change the font to the one specified by the alphabet. If the user enters a font dialog box while the alphabet is selected, pop up an alert first, "The current alphabet requires the use of the XXX font. Are you sure you wish to change font?".  When the user changes to an alphabet which does not specify a font, then, if the user has not changed font while the font-specifying alphabet was selected, restore the saved font settings.