The characters in Lio know they live in a comic strip. Creator Mark Tatulli has shown them breaking through the panel borders many times, escaping into neighboring comic strips (or having those characters wonder into Lio). The sequence published 4/27/16 is a little different, though.
The power of this sequence comes from its ambiguity. The first panel's plain enough -- Lio paints a diamond on a wall.
But that second panel.
Tatulli regularly depicts the outdoors as he does in that second panel -- a grassy foreground strip across the bottom of the panel, and then a big white space for the sky.
So is Lio holding a string attached to a diamond painted on a wall, or between panels has that wall vanished the diamond become a kite? The simplicity of the illustration doesn't provide enough information for us to say. And that's the point.