On my Ubuntu 12.04 Linux 3.2.0-43-generic system with AMD Athlon 64 X2 5000+ cpu, with Unity desktop, ubuntu-2d desktop-session, and Metacity window manager, some of the tabs on a GNOME Terminal 188.8.131.52 display look like depressed buttons, while others don't. The appearances when I click a tab and then click in the pane are illustrated below (in five pictures, for five tabs left to right).
When the pane for tab 1021 is in use (first picture), the sp tab looks like a depressed (or perhaps selected) button. When the pane for tab sp is in use (second picture), other tabs properly look unselected. When the pane for tab py is in use(fourth picture), the ipy --pylab tab looks selected, and vice versa.
Question: Why are some tabs displaying differently than the others?
Note, for reference the picture below shows the appearance after the sequence of clicking the ip --pylab tab and then the 1021 tab (without clicks in panes).