The identifier $sline(window,0) - returns nothing if there are no selected lines in the list.
It is logical to assume that the answer should be = 0. The returned numeric value is meaningful in some cases. For example, when using an enumeration in a loop "While".

For check:
//sline -r #test | echo -a $sline(#test,0)

Returns: * /echo: insufficient parameters

Would like to the returned response was as ยซ0ยป (exact number) to be able to take the necessary steps to highlight a specific line in the window list:
if ($nick(#test,0) > 0 && $sline(#test,0) == 0) { /sline -l #test 1 }

Otherwise, it is likely that the script with a similar string "IF" condition will not bring the desired result or will crashes. Thanks.

๐ŸŒ ๐Ÿ“œ 6667 #Code (mIRC scripts, help, discuss, examples)