Feature Request: Ext.selection.CellModelView mode:MULTI

I love the grid, but it has one key limitation from allowing it to be used like a spreadsheet -- the inability to select multiple cells (across columns or rows).

Please consider adding support for mode: MULTI to Ext.selection.CellModelView. People have been asking for this since at least 2008:

http://ift.tt/1mj9Dru

I know there could be some challenges and limitations when dealing with frozen columns, etc., but anything would be an improvement.