Comment 9 for bug 1647292

You can test the following "hack", Massimo:
Run terminator using the following:

GTK_DEBUG=interactive terminator

In the CSS tab (at the top) You can insert the following CSS snippet:

GtkPaned {
    margin: 0 0 0 0;
    padding: 0 0 0 0;
}

You should find that that annoying hover issue goes away temporarily, and you can now select characters next to the splitter handle.

I'm seeing that the GTK3/CSS is causing a number of pain points that mean a thorough good revision is needed anyway, so perhaps this can be rolled into that.