This utility came in handy when using the free version of VNC Viewer on a system that has two monitors. In this viewer you only can view the main monitor so if a window opens up on the second you won't be able to see it. With Multi-Monitor you can at least see the second screen. The downside is you cannot click on anything in that windows but at least you know you can see the screen.
If you find yourself in a similar situation you might find this of use as well.
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