Strange Wpf Ballon behavior after unlocking pc

I have a wpf application that runs some threads every x minutes and I noticed that if I block the pc 开发者_C百科and than unblock it after some time, all the balloons messages that were supposed to display during the time my pc was locked are displayed when I unlock the pc (like they were waiting for the gui to come back). Is that a normal behaviour? Is there any way to avoid this?

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I don't know whether or not this is intended behavior but I think it is justified in most cases.

Here is a way to find out if the PC is locked so you can suppress popups (if that is what you want)