How to activate the menu Item « Merge all windows » for my application ?

Hi (from France),

I cant’n find anywhere  the way for activating the menu Item « Merge all windows ».

It seems to work for Apple applications so there must be a way but how can I activate this item for my own application ?

Best regards, Laurent

How to activate the menu Item « Merge all windows » for my application ?
 
 
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