Block Screen Capture
BlockScreenCapture is a sandbox setting in Sandboxie Ini available since v1.13.6 / 5.68.6. If enabled, it will prevent sandboxed processes from accessing the images of the window outside the sandbox. For example:
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[DefaultBox]
BlockScreenCapture=y
A setting similar to BlockScreenCapture is CoverBoxedWindows.
Related Sandboxie Plus setting: Sandbox Options > General Options > Restrictions > Prevent sandboxed processes from capturing window images