Screenshot of selected area with shadow?
Grab doesn't generate the shadow when a Window is copied, it copies the shadow that the OS has already applied to each window.

However, If you want to apply a shadow to your screen shots it can be done with extra steps using other applications.

If you have Keynote or Pages installed, you can replicate it with a few steps.


Open Keynote or Pages (instructions same after this point)
Select a template.  The background does not matter but white shows your work better
Drag or paste in your screenshot.  Note: Using control+⌘+shift+4 you can send your screenshot directly to the clipboard.
Apply a drop shadow to your image
Select and copy just the image and paste it into your email or desired location.


See images below:

Original Screenshot:



Keynote modification:



Result: