Ribbon Command Setup
Here we pass the SelectedControlSelectedItemIds which will pass an object array of all the record ids that are selected on the home grid.
The web resource will data the ids and post them to a new variable in the main XRM window then opens a popup window.
This popup page will get the ids from the page that opened it. In order to do so we need to do the following:
-declare the array to hold the id values
-copy the values from the object in the parent page to the array you created