I can easily apply a single mask or rotoscoped area to a clip to reveal an underlying clip, but how can I do this with multiple areas?

For example, the top clip (not an image) is a window frame with 4 panes of glass. Under it is a clip of clouds moving in the sky. How can I mask 4 separate areas on the top clip?

Add three more rotoscope effects to the clip

If the areas you want to a rectangular shapes with 90 degree angles you can use the Alpha Shapes effect multiple times to do that too. Rotoscope is more flexible for irregular shapes but trickier to apply due to the bezier shapes.

I saw this in another video on Shotcut about blurring multiple people in a clip, which would be a handy thing to do.

Thank you berndmj.

I tried this out applying 2 alpha shape mask effects applied to different spots on the clip with operation = subtract. I then applied a rotoscope mask with mode= alpha and alpha operation = subtract.