it would be lovley to have such a feature. as I simply hate the big square popping up all the time when contacts are signing in. and if you turn it off, you don't notice when friends do login (without using the great feature of "display on desktop" on contacts...). What would be nice would just be a small popup above the tray, just where the normal alerts come, but just minimal window and  L: NICK     (for logins) and M: NICK   for messages. or something like that....hope you understand...

Messenerg Plus! mimics the standard toasts of Messenger. And that is a good thing. As soon as Messenger changes his toasts to something like that, I'm sure Patchou will follow. But for now, I highly doubt it that it will be a feature...

However, This could be done with a plugin (given that you disable all the toasts in Messenger and Messenger Plus!). This plugin doesn't exist yet though. So if a plugin maker sees this and wants to make it, you have a chance, otherwise, nope sorry....