Try
function OnInit(initData) {
initData.name = 'TabDepth';
initData.default_enable = true;
}
function OnAfterFolderChange(afterFolderChangeData) {
var currenttab = afterFolderChangeData.tab;
var td = currenttab.path.components;
DOpus.Output('Tab Depth = ' + td);
}
See also here.