BSP and session management

Hi everyone, I am doing development with BSPs in CRM People-Centric UI. Here's something that is puzzling me... when a BSP calls another using the BSP extension "BSP" "CALL" from within a view, under what circumstances is another terminal session launched?

In my case, I am calling a screen of type "Preview" which means in real terms that a URL is constructed with the name of a new BSP and its controller. The URL is then launched by view code that looks like this:

<script language="JavaScript" type="text/javascript">

window.open("<%= gv_url %>", "Preview");

//window.open();

</script>

After this, the new browser window opens with the url displayed at the top. The controller class executes (do_request method).

OK so far. Here's my question... this new window sometimes executes in the original terminal session, and sometimes not! This affects debugging and more importantly program execution, since the code in the second window gets its data by an IMPORT FROM SHARED MEMORY command. If the new code is in a separate terminal session, the logic fails. This is SAP code, not my code!

When does this happen? Yesterday, I could get the same terminal session (and program success) by starting the BSP from within an open CRM SAPGUI session. The different terminal session (program failure) happens if you start the application from the internet browser directly. Today, even starting from SAPGUI is triggering a separate terminal session. Can anyone help me to track down where the same session/different session decision happens?