Prevent deselect of xtype:checkbox based on condition in ExtJS 5.1

ExtJS 5.1

In xtype: 'checkbox'

I want to add a condition before deselect checkbox based on condition. According to my research, I got only one event change that fire when we check or uncheck check box. I can get checkbox is true or false.

But i want to fire event before deselect of check, so that i can add a condition and if condition is false then i return false and checkbox will not be unchecked.