Source / Masks / Effects & Masks effect option scriptable
It is possible to set and change each property of the effects with a layer selection dropdown (such as Set Matte or Compound Arithmetic) via scripting, however the selection for 'Source / Mask / Effects & Masks' is currently inaccessible (via script).
Please reveal this dropdown property to the Extendscript API for all effects with a layer selection dropdown.
Screenshot of this inaccessible dropdown is attached.

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Constantin Maier commented
This feature is truly missing. It would make sooo much possible if it would be scriptable and I imagine it wouldn't be that difficult to offer that option in the API.
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Andru Phoenix commented
Been waiting on this for years now.. this would open up doors for layer instancing tools. I pretty much use the effects you mentioned to keep everything in one comp but it can be very tedious because setup can't be automated.
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Steven Twigg commented
This would be very useful, and seems very easy to implement (?).
P.S. the work around for this is to create a set-matte preset with the setting how you'd like, convert the .ffx preset file to binary, and have your script save that binary to a .ffx file when needed then apply it. Give a google for how to read/write files if needed.
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Bill Ullo commented
Would appreciate access to this attribute as well. Thank you.
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hamid ahmadi commented
We are waiting for it !!
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chifei soong commented
Please make this property scriptpable, thanks :)