I have a Grid panel generated for the property model:

X.GridPanelFor(m => m.InvoiceItems, false, true, false)
True means that the Store is generated for this grid.

I cannot add a Store ID property for this grid because I get an error

X.GridPanelFor(m => m.InvoiceItems, false, true, false)
                            .StoreID("StoreName")
Error:

Please do not set both the StoreID property on GridPanelCust and inner property at the same time.
I have tried pulling out the store ID from code like this:

App.GridPanelCust.getStore().getId()
But the error reported is that the

getId() is not a function
Anyone know how can I pull out the Store ID from GridPanelFor generated one?