The Snapshot Delay: box allows you to enter an arbitrary time delay, in seconds, between the time that you press the button and the time that the snapshot is taken.
When a delay time has been set, you do not have to click the mouse button to capture a screenshot. This enables you to open a drop down menu, and take a picture of it.
Include window decorations is enabled by default.
When you only want to capture the application itself without the surrounding window decoration, disable this option and take a new snapshot.
When you want to print your snapshot from the preview, just click and you get the standard KDE Print dialog, from where you can directly print your snapshot.