There is a post in Flex component Yahoo group on how to show a 3-state checkbox in an AdvancedDataGrid.
It has been implemented for the Flex Tree Control in the Flex cookbook.
I thought lets write a similar example for AdvancedDataGrid. I made some changes in the original sample and here it is; working for the AdvancedDataGrid control.
This example shows how AdvancedDataGrid can be configured to show summary with the Group node.
Here, I’m using GroupingCollection to calculate the Summary with summaryPlacement being “group”. Then using groupLabelFunction in AdvancedDataGrid and returning the Group Node’s value plus the Summary value.
Source mxml is located here.