I'm somewhat at loss how to use the row editor with Ext JS 4.0-pr3.
I copied the example from version 3 and removed the 'ux' from Ext.ux.grid.RowEditor since there is now a RowEditor in Ext.grid.
Unfortunately this fails with the following message in Firebug:
plugin.init is not a function
at ext-all-debug.js (line 35203).
Isn't the row editor a plugin anymore?