how to change the character of this vertical line?

[hopezh]

As shown below, which option should I use to change the character for this vertical line highlighting the current context?

[lukas-reineke]

It's :help ibl.config.scope.char

[hopezh]

I used the following config of char=":", but the character representing the vertical line doesn't seem to change. Have I missed anything important here?

[lukas-reineke]

scope char without indent char is currently not supported.