How can I create the autocomplete for the function with opening file selection dialog? For example like a autocomplete of the SystemOpen

UPD: the answer to the question is contained in this post

• See the “custom autocompletions” section. The number you pass to FEPrivateAddSpecialArgFunction` or whatever it is is like 3 I think. It’s undocumented but on the site somewhere. – b3m2a1 Aug 18 '18 at 21:28
• @b3m2a1 Where can I find the "custom autocompletions section"? – C. E. Aug 19 '18 at 8:36
• @C.E. Sorry I meant question. Szabolcs has one like this. – b3m2a1 Aug 20 '18 at 4:32
• @b3m2a1, You could just leave a link and say that this is a related question, instead of hinting that somewhere there is something similar mathematica.stackexchange.com/questions/56984/… – Kirill Belov Aug 20 '18 at 6:58
• @KirillBelov I didn’t have time to track it down when I left that comment – b3m2a1 Aug 20 '18 at 13:36