Grid: Initial checkbox state in Grid.

[GMatrixGames]

Would be quite useful to have a way to set the initial checkbox state of specific items in grid based on a boolean return.

For my use case, I am using a Grid to select items to be included in a set of data, but need the already selected products to be shown as enabled so they don't get selected a second time.

[garyravago]

I also ran into this scenario and definitely would like to have this considered for future Grid enhancement