[Indlinux-group] cursor and delete/backspace behavior

[Bernard M. <bm...@fr...>]

Hello,

I've just tested, one after all, programs of main graphics libraries 
families to see if it improved since the last time I did so. And it did. 
However something that stroke me is the lack of consistency in the way 
cursor and delete/backspace keys behave, especially when considering 
consonant clusters.

Qt and basic KDE applications treat clusters as single graphemes when 
moving cursor, they use <backspace> to delete one Unicode character and 
<delete> to delete the entire cluster. In Kate, <delete> deletes only 
one Unicode character, even in clusters, resulting in isolated viramas 
or matras. In KWord, both <backspace> and <delete> delete the entire 
cluster. OpenOffice.org and Firefox treat clusters as a list of 
{consonant,virama} couples with an optional matra for the last one, 
sometimes resulting in very disturbing cursor positioning (in the middle 
of a character), or in giving the impression that you have selected a 
whole cluster while in reality you only have a part of it in the copy 
buffer (you can also type text in the middle of a cluster in a totally 
unintended way), or you can even have the cursor moving to the right 
when pressing <left>.
A real mess!

So my question is : is there any more or less official standard about 
cursor and delete/backspace behavior ?

Unicode has the 
http://www.unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries page 
which suggests something very close to what Qt does, but it's not 
written as a standard you're supposed to follow but more as mere 
suggestions and examples.
It seems to me that Qt, at least for scripts which have complex 
consonants clusters (I agree Devanagari and Tamil may deserve different 
treatments), is the only one behaving the right way, and OpenOffice.org 
and Firefox are the most broken. But it would be nice to know what is 
supposed to be "the right way".

Regards,
-- 
Bernard Massot