Your comments

I don't understand why this feature isn't built-in any text editor.

Yes, the fact that it is possible to do it with a plugin is very nice. I was actually considering giving a more in-depth look at your plugin to understand why it doesn't behave as what I expect. Thanks anyway

Last time I searched for this, it was apparently not possible - at least now there seems to be a way.
But this plugin (as well as the one on which it is based) does not work. It looks like it only records the position of the selections, which is far from being useful.
This missing feature is the only reason why I can't use ST right now.
Visual Studio and Eclipse have this.