Final answer:
When CTRL + SHIFT is clicked on a region with the OPT key depressed while the F8 tool (grabber) is active, it typically allows the user to capture a screenshot of the selected region.
Step-by-step explanation:
When the F8 tool (grabber) is active, pressing CTRL + SHIFT and clicking on a region with the OPT key depressed usually enables the user to capture a screenshot of the selected region. However, the exact functionality of this key combination may vary depending on the specific software or operating system being used.