Sclender's mouse support is compatible with Oracle Virtual Box, which allows you to run multiple operating systems on your machine at the same time.
To use mouse with Virtual Box, you must enable Virtual Box's mouse capture feature.

First, check the "Use with Virtual Box" checkbox.

Select your filters as normal (for this example, we use Scanlines). Attach Sclender to the window for your running virtual machine.

To activate mouse capture, either select the feature from the VM menu Bar (under Input -> Mouse Integration) or press and hold the "Host" key (right CTRL by default) while pressing F12.

You'll see the arrow next to the mouse icon at bottom right turn from green to yellow.

This means mouse capture is enabled.

Next you need to help Virtual Box capture the mouse. Notice that there is a sliver of "daylight" between the filter and the VM window title.

Click in that area if you can. If it's too small to click in easily (such as on a small screen or high resolution) you can increase the size of the gap by setting/increasing the filter's X offset.

The mouse is now captured and usable in the filtered area.

To free the mouse, press the "Host" key (Right CTRL). To capture the mouse again, either click in the exposed area or press the "Host" key.