Before the DBCS OS/2 2.0 version, there are only monospace MBCS fonts. Application programs may have assumed the MBCS fonts are always monospace fonts and handled the font size without taking care of the average character width value. From DBCS OS/2 2.0, the proportional MBCS fonts are supported, (actually the fonts data for SBCS characters are proportional and fonts for DBCS characters are fixed pitch) and becomes the system default font. This change affected the applications that did not handle the font correctly in 1.x version.