As deAd said, you have to use the DisplayToastContact rather than just DisplayToast like in the code below. DisplayToastContact goes in the following order - title,unformatted line,formatted line, sound,......
In DisplayToast it is missing the unformatted line so you won't be able to bold it. An example of it in use is below, it is for blocking a contact an having their emil be bolded in a toast when you do
code:
function OnEvent_ContactBlocked(Email)
{
var Message = "<b>" + Email + "</b>"
MsgPlus.DisplayToastContact("",Message,"",'notify.mp3')
}
NB. I wrote the bold in HTML rather than BBcode because I don't know how to turn this off