Get checkbox event count on screen

[hemant123]

I am using xtype:'checkcolumn', I need to get the count of changes done on the checkbox. It means if suppose the checkbox already checked and I uncheck it I should get count as 1, and when i checked it again the count should go to 0. I need to show the count in my UI as a message in table header.

[mitchellsimoens]

Use the check event and update the component that holds the count.