Set 40/80/90 columns, 12 to 80 rows, change windowed DOS-box size. C source.
Text Mode provides control of various text screen settings:

columns (40, 80 and 90);
rows (most values from 12 to 80);
scan lines (200, 350, 400 and 480);
font height (6 to 16, or from file);
page (usually theres more than one text screen);
screen and Border color.
It can also display the current settings.

In addition, resident programs are provided to make your font and color settings permanent.

Windowed Text Mode can set columns (2 to 132, even) and rows (1 to 128) for windowed DOS-boxes. you can free download Text Mode 0305 now.