You can copy C code from a web page and compile it because it's still in text form and made up of individual characters that can be parsed. A .gif or similar image file is simply one object - if you took a screendump of a text editor containing C source code you'd have to have a program that identified all the text characters in the picture in order to generate a text file to compile.
Trying to do something similar with LabVIEW would be a nightmare - you'd need some way of identifying every function and sub-VI icon and matching it to a sub-VI somewhere on the PC's hard drive, including icons you've made for your own sub-VIs and possibly dealing with duplicates. Not forgetting you'd need to work out where all the wires were going, including ones which cross over, to get the dataflow. And as for the hidden frames in Case and Sequence structures etc...
