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If pressCount is 1, then ++pressCount % 2 would be 0. I suppose there might be some sequence point issues going on.

Of course it will.

You call it pressCount everywhere else, why not that line too?

How fast do you need to press the enter key? If speed isn't an issue, then you can just, in your VK_RETURN case, count how many times you've been there -- the first time show the picture, the second...