When I open a terminal in Ubuntu 15.04, it shrinks to 1 character by 1 character. I can use the corner resizer to make the window bigger, but it immediately shrinks to 1x1. There are a few x,y combinations that allow the window to stay at the desired size, but if you're off by a pixel, the window shrinks to 1x1.
There is another question, Gnome-terminal in Kubuntu shrinks to minimum size, that is basically the same thing, but in KDE. I tried to follow the instructions:
In KDE, go to System Settings. Return to the overview if you are not already there. In the Workspace Appearance and Behavior section, click Window Behavior. In the area to the left, click the Window Rules icon.
but, there is no Workspace Appearance and Behavior section. I couldn't find a similar setting in ccsm, gnome-tweak-tool or unity-tweak-tool.
% dpkg-query --show compiz compiz 1:0.9.12.1+15.04.20150410.1-0ubuntu1 % dpkg-query --show unity unity 7.3.2+15.04.20150420-0ubuntu1
The problem appears to be in the Adwaita theme. To avoid this problem, I opened the System Settings/Appearance and set the Theme to Ambiance (default).