looks good, but hmm its really hard to guess characters script when it will be alone. I think one need to add extra check, when character will be at initial position with property inherited
Indeed, if the text is simply some base character of script Common (NBSP, dotted circle) + one of those marks which are not script specific, then there is no good way to assign a script.
On the other hand, one could expect that any "script engine module" (and not just an Indic or Devanagari one), in particular when using OT, should be able to do the right thing. There is no more magic about U+0951 ◌॑ DEVANAGARI STRESS SIGN UDATTA than about U+0301 ◌́ COMBINING ACUTE ACCENT. Rather than ask for the change of the script property for 0951/2, I would look carefully at the font: it will probaby help to have some shaping under the default script.
Eric.
