B4i Msgbox2 in general works like B4A Msgbox2Async. The dialog is not a modal.
For example, Msgbox2("Msg", "Do you want to do delete document?", "Title", Array ("Yes", "No")).
To retrieve the answer, you can use Wait For Msg_Click (ButtonText As String) or separate subroutine Private Sub Msg_Click (ButtonText As String) ... End Sub
B4A Msgbox2Async has special parameter - Icon
B4I Msgbox2 doesn't have similar parameter. Nothing terrible. If you need simple alert, Msgbox2 is enough. If you want really custom message, create a Panel with own elements.