sandboxed poppeeper: how to minimize window

Using Sandboxie's "Add Shortcut Icons" feature I made a shortcut for the poppeeper application.I moved that shortcut into my startup group to make poppeeper start with my computer.
I am using sandboxed poppeeper happily. But I want to change one thing.When I start up my computer poppeeper window is on the desktop,I do not want it to be on the desktop ,I want it to be minimized in the taskbar.Is there a way to change this?
I think it has to be done in the registry like the avira free nosplash trick.But I do not have enough knowledge.I will be very happy if someone helps.