Invisible "wall" at iron bars and glass panes

Please attach a screenshot.

how to make a screenshot of an invinsible wall?

all I can do

Don't understand.

the side of the bars is invisible in the inside

How to catch a lion

The method of inversive geometry. Place a locked, spherical cage in the desert, empty of lions, and enter it. Invert with respect to the cage. This maps the lion to the interior of the cage, and you outside it.

Lol i think you didn't understand the title 😛

In fact, the block is visually not "closed", as if there was an invisible block.

Your description does somewhat not match with the description of this ticket:

If 3 ironbars or glass panes are conected the central bar/pane has a hitbox like a block.

Finally could confirm this in 14w26a and the fix in 14w26c.

@unknown: In your screenshot the hitbox is show "Sand"...