original idea/google thread: https://groups.google.com/forum/#!topic/idempiere/m_2u9aGA370
Overview - We suggest to follow the next strategy:
extend t_selection by universal columns e.g. col1, col2, colN (e.g. 10) where we will be stored other columns of selected rows from info window. Maybe columns with isIdentifier='Y' could be stored in t_selection (what is a goal of field Identifier in info window field?). Then we can create database view where will be one column with Table ID and use this column in info window and process.
Next extensions could be storing Info Window table ID in variable m_Table_ID and new variable m_InfoWindow_ID in ProcessInfo class.