Well, I got it to work by programmatically setting the font face from the beginning upon init of the composition. In case others run into the same issue, this worked for me:
var toggleButton = sym.getSymbol("captionButton").$("textBox");
I was unable to reproduce this on our side. Could you send us a link to your project so that we can take a look at it?
You mean I have to break it again ;-) OK, I'll try to find a previous version. OK, I commented out the css setting on init and the css settings when the caption button is clicked.
whoops. looks like a bad upload. I'll try again in a few minutes.
OK, uploaded. Sorry I had to include some assets just so it would load but it's all in a zip file. Ironically, downloading it to test it, it doesn't change to bold but it does seem to change fontfamily so the concept is the same.