Add a drop shadow
Before proceeding with this topic you need know how to work with selections.
The "Drop Shadow" effect permits to simulate a shadow behind an icon to produce a false 3D effect. Adding this shadow is important to make Windows® XP compliant icons. It is part of the Windows® XP icon specifications as published by Microsoft®.
This feature works only with RGB/Alpha Channel image formats.
Apply the drop shadow effect
1. Select a region with the selection tool or use a floating selection. If no selection is active, the adjustments will apply to the whole image.
2. Choose Draw/Adjustments-Effects/Drop Shadow or press "D".
3. The drop shadow is applied immediately. Repeat the operation to create a stronger shadow.