Render of Thai text with and without mouse selection

[Pattara Kiatisevi]

Hello kfm-devel,

I'm not sure if this is a problem of KHTML but maybe you guys here 
have a clue. The problem is for some Thai texts, rendering becomes 
different when one selects that text with mouse.

Here is the illustration (animated-GIF):
http://webls.ex.nii.ac.jp/~pattara/tmp/kde-highlight-problem.gif

The text in the input box (first frame) is rendered correctly.
The text without mouse selection (second frame) is most wrong.
The text with mouse selection (third frame) seems to be almost correct 
but at the end of the string, there is an extra MAI_TO vowel (maybe 
remnant from the second frame).

Cheers,
Otto