Split indicator on parent container

[sherminator7]

Hi,

I know we are not accepting new features unless i3 implement them but I thought this was more like completing what's already there rather than a new feature. In which case you disagree I would have tried my luck.
We get to see the split indicator on a window which is handy but, unless I'm mistaken, we don't when focused on a parent container and I thought it was relevant too when wanting to split container a certain way.

What I'm asking for is a split indicator on parent container.

Having the indicator on the right side of the parent container of the two windows:

|---------------------------------------------||
|                                             ||
|                                             ||
|---------------------------------------------||
|                                             ||
|                                             ||
|---------------------------------------------||

When opening a new window, this'd give something like this:

|-----------------------|---------------------|
|                       |                     |
|                       |                     |
|-----------------------|                     |
|                       |                     |
|                       |                     |
|-----------------------|---------------------|

I hope I was clear enough, thanks for reading my post.