I am currently developing a Facebook canvas app in which I allow users to invite others to use the app, which is pretty standard. For this, I use the FB.ui JavaScript SDK method.
FB.ui({
method: 'apprequests',
title: "Title",
message: 'Custom Message',
to: UserIDs
});
This user interface dialog is currently displayed. See this image (note the preview section with a standard prompt):

: USER_NAME sent you a APP_NAME request. , , , ( , !).
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