Eagle learning notes

Here are some extra notes when learning the book of Make Your Own PCBs with EAGLE : From Schematic Designs to Finished Boards. 

*Install Third-party Libraries
In the book, it mentioned installing the Sparkfun library and the Adafruit library. For a project to use the libraries newly installed, we need to right click the directories of the libraries and select the "use all" menu item in the pop up context menu.

* Undo autorouting
Want to undo the work of autorouting and didn't find any button that can do that. Fortunately I found a tip shared in Ref [1]. Just go to the command input box and enter the command "ripup;". It works.

Reference
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1. http://43oh.com/2011/11/tip-eagle-pcb-undo-autorouting-in-one-step/