Steps to reproduce the issue
1) start chat with a person
2) invite a friend to create a conversation
3) type string ????????????/////////////// by below:
hold down shift key and press '/' to input series of ?'s, 
then let go of shift key to input /'s

this results in conversation window's size increasing towards right to 
show the slashes instead of creating new line like in normal input case.

Similar bug exists in previous versions where when "show contact list" is
enabled, conversation window's size also increases towards right when typing 
sequence of strings longer than input window can provide horizontally.