where i leave onBeforeEditStart with
return false;
the tab order stops at this point of editing.
Is there a workaround for this?
(changed the bug message )
Following Workaround works only for TAB, but not for Back-Tab (shift-Tab):
var nextcol = this.columnId( this.getColumnIndex(id.column) + 1);
if (nextcol) this.editCell(id.row, nextcol, false, true);
return false;
and that workaround makes problem on direct click/dblclick to the (temporary) forbidden cell… :-(((
hoping for some good code suggest 
I can confirm the issue.
We will try to provide some workaround in next few days.