AndEngine classes - problems with opening declarations: Source not found

Im working with AndEngine in eclipse (which is a 2d physics/tiling engine) Everything works fine yet when i try to open declaration to classes I get Source not found I can Change Attached Source... but i wouldnt know what to change it too... is there a way i can download the classes so i can view them on my computer (so far im stuck with googling each class and it slows d开发者_开发技巧own my progress immensely)

Is this suppose to be happening? Can i somehow solve this problem or get my hands on some good documentation.

I fixed the problem by extracting the jar file with the JD GUI program. Then i simply opened the declaration and then clicked change attached source... and pointed it to the file (which is still zipped it doesnt work if you unzip it) Everything works well now :D