Brad,
I had this same problem with wanting a close from using a button with contentURL and I found a workaround, but due to Javascript security, you must be on the same domain (which shouldn't be a problem for most implementations).
On the page run by the ContentURL, you will just need to emit the following Javascript when you are done with the dialog:
Code: Visual Basic.NET
Response.Write("<script>parent.eo_GetObject('dlgNameHere').accept();</script>")
The key is to use the "parent" keyword and then you have access to EO's stuff. I put mine in a Postback Submit, such that:
Code: Visual Basic.NET
Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click
' Business logic goes here
' If something goes wrong, use Exit Sub to prevent the dialog from closing or other error handling
' Successfully done with business logic, want to close the dialog
Response.Write("<script>parent.eo_GetObject('dlgSubeditor').accept();</script>")
End Sub
It is working well for me and properly doing both the postback/business logic, and then closing when done, all from a single button on the ContentURL.