Recent tests show that Shadowmeld for Rogues now finally works very similar to Stealth (Druids have been able to use Stealth abilities out of Shadowmeld for much longer), so I wondered if it was possible to make the stealth bar activate also when in Shadowmeld (to be more exact, not only activate, but page just like for normal stealth).

I couldn't find a way currently, so I simply added a
addState('class', 'shadowmeld', '[stealth]', GetSpellInfo(58984))
to barStates.lua under the class == "ROGUE" section, which seems to do the job just fine.

Of course this must be adapted for other races and classes (Shadowmled seems to work for Warriors with Charge as well for example), but for me it's sufficient.

Sounds like a reasonable thing to implement.