Have you ever seen something in the APEX Developer application and wonder how the APEX team built it? Since APEX is built in APEX you can actually see the code for the development environment. The way to do this is to install APEX in APEX. When you download APEX you also get all the development/builder application files:
Simply install each of the applications into a workspace:
Note: Since some of the builder files are extremely large it does take a while to install and you may get a timeout error.