Ok, i read the source code of UIGrid and know that it actually don't make any touches processing. I asked in common - how to detect which item selected and what approach i should use - add button, subclass the UIDragPanelContents, or something else?
P.S. I found NGUI only few days ago and don't understand some of it's approaches, it's much differ from native iOS/android flow with delegate/listener asynchronous patterns.