In general it´s good to have dynamic save-style acitvated. So greenshot is asking for saving here oder uploading on imgur etc.
But sometimes, ingame, you like to have a shortcut for direct screenshot without opening the dynamic-save-menu. But you won´t to disable the dynamic-save-feature.
So an Shortcut would be nice for savin the screenshot directly to the default-folder. strg+shift+print. And no windows is popping up.