1. M-x shell                                   ;; Invoke a shell buffer
2. Issue shell command "tput cols"             ;; Query terminfo database for number of columns
3. Output: 168                                 ;; You may get something different depending on your setup
4. Press "C-x C--"                             ;; Decrease the default face height by one step
5. Issue shell command "tput cols" again
6. Output: 168                                 ;; Did not change but should have increased since text face has decreased
7. Press "C-x b RET"                           ;; Change to some other buffer
8. Press "C-x b RET" again                     ;; Change back to original *shell* buffer
9. Issue shell command "tput cols" for the 3rd time
10. Output: 192                                ;; The correct number of columns is finally shown