How to make tabs in blender?

I have seen this tutorial of https://wiki.blender.org/index.php/Dev:Source/UI/Tutorials/AddAnEditor
And made a “Tabs Editor”.
When I made it it was blank empty but I want to change to Tool Tab in View3D In It.
https://drive.google.com/open?id=1B3TsjLxKGkSQ5kJSZtbWKIZxYmly865D
But 90 degrees rotated.