It's because i don't have one of these.
this is a little mock up i did today demonstrating what i'd like to see in a messenger app. pretty much a panel applet.
Disclaimer: the following is a bunch of my opinions and a description of the Functionality i'd like to see in a messages panel app.
here, i'll throw some opinions at ya. a floating window or widget is not practical, although a window is better than a widget it's still too slow. messaging should be an integrated function ever accessible in the form of a notification. it should at any time appear over whatever you're doing in one click or less. you should NEVER need to move a window to access messages.
Functionality? so, default state is just the contact list. i mocked up that as well but got lazy doing the screenshot. once click on a contact will automatically extend the message panel. one click on a contact while a message is currently active in the message panel will add a tab and make it active on the panel. closing all tabs will un-extend the messages panel. it's just that simple. you may notice the redundancy of that first drop menu item. sorry i got lazy. the drop menu quickly serves up options for individual contacts.
the options panel slides down when you click the gear and offers various quick options. you can toggle various accounts on/off and hide or change stuff. THAT IS THE ENTIRE OPTIONS PANEL
the add account button will open a sign in dialog over the message panel. so, in effect you will NEVER leave this one simple panel. it's powerful and stupid simple
btw, scroll bar appears (rendered OVER content) on hover or while using the wheel. scroll bars are over rated.
my compliments to the elementary os
crew for inspiration.