One of the main features of this program was that interaction required from the user is minimal - mainly, you just click one button and everything happens automatically, both transport creation/release/import, as well as refreshing table with information about success or failure. Meaning, you don't have to constantly mash "refresh" button to get information whether toc is yet imported or not.

With that in mind, and the fact that the whole process blocks UI, as well as that it's not entirely synchronous, and toc import can be called before it's fully released, I thought about making it asynchronous - but dropped the idea because of some problems.

First idea was to use cl_gui_timer to run background checks every few seconds and refresh GUI accordingly - unfortunately, this class is not reliable since if the GUI is blocked at the moment of call, it's not executed, and isn't even scheduled for the next call. This problem is known and won't be fixed by SAP: https://me.sap.com/notes/2679117.

Another was to use function modules with starting new task, but the problem there is that you can't refresh screen in callback module, e.g. via alv_table->refresh( ) (I'm guessing it's because callback is called in another thread or something?), thus requiring additional input from user. And I don't think wrapping everything in function modules and callbacks would improve code readability. :P

So for now I just added option to retry import for some time in case you have ToCs which aren't visible immediately. If somebody have an alternative solution I would be happy to hear it. :)