using tabs, gets confused when different lines in different tabs

[cc young]

using more than one tab, if you cntl-minus to make text smaller in one tab, when you go to a tab that retained the regular size, it puts in extra blank lines

first tab:
$ vim <large file>

second tab:
$ psql (or other readline app)

first tab:
shift-minus (to make font smaller = more lines per page)

second tab:
(extra blank lines have been inserted)
(if editing, will mess up edits)