Consider this:
menu nicklist {
  $qt($0) - $qt($1-) : echo -a $0 -- $qt($1-) -- $qt($sline($active,1)) -- $qt($snicks)
If nothing is selected in the nicklist, right clicking an empty area of the nicklist trigger the menu but:
-the value of $0 is 1 when the menu is displayed while $1 is $null
-the value is correctly set to 0 when you execute the command.

Same problem occurs if you select more than one (let's say 2) nickname and then rightclick on one of them, the value of $0 is 1 and only $1 exists before executing the command, after, values are correct.

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