Lao Font Problems
Since Lao has never been fully supported by Microsoft, many Lao fonts do not display correctly in Windows applications. Lao Unicode fonts (such as Saysettha OT and Microsoft's DokChampa) that have been especially developed for use with Windows applications will usually display correctly, but other Lao Unicode fonts (such as Arial Unicode MS, some versions of Phetsarath OT, Saysettha Unicode) even though they use correct Unicode coding, may not position the vowels and tone marks correctly, or may have other display problems.
For further discussion of Lao font issues, see the Fonts section of Frequently Asked Questions.