mcedit: undo warning

["Dmitry L." <dim0xff gmail com>]

Hello!

It looks like a bug for me.
In mcedit I have next warning when remove block of text (when length
is large than 16384): "Block is large, you may not be able to undo
this action"

But actually I can undo only when remove block of text with length
less than 8190.

So, when I remove block of text where 8190 <= length <=16384 I don't
get any warning and can't undo this action.

PS: I'm using MCEdit 4.8.19 from Arch Linux repos

-- 
//wbr, Dmitry L.