Hey, a Debian user reported (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=574493) some issues with vertical and general maximisation. Basically sometimes the maximisation is done on the window and sometimes on the vte widget (I guess) meaning sometimes the step is the terminal line and sometimes it's the pixel. That plus when the terminal is vertically maximised, opening a new tab expands the window below the edge of the screen.
Resolved by migrating to vte3.