OK I don't think we are understand each other at all. I'll start again from the top.
I require a chat dialog box. I can have zero or more dialogs on screen at any one time. Each dialog should be resizeable and dragable, ie the user can change the size and/or position of the dialog. If the user clicks on the dialog within x pixels of any edge the dialog goes into resize mode and the user can drag the edge to whichever extent they like; otherwise the dialog is simply dragged to a new location. This is pretty standard behaviour for chat dialogs in general.
My Problem is NGUI does not support this resizing natively so I have to write something. So how do I turn off the automatic drag functionality when the user is near an edge of the dialog, so that can intercept the OnDrag calls and resize the dialog?
The dialog is designed as follows; UIPanel with DraggablePanel script, SlicedSprite with DraggablePanelContents script. Dragging works fine. Now I have to figure out resizing.