Hi Kathiresan,
What you are looking for is located inside of EP-RUNTIME SCA
The component file is com.sap.portal.pagebuilder.SDA
inside you will find the JAR file for pagebuilder (inside of the war file of course).
Inside of that JAR file there are 2 classes that really interest you:
1. PageBuilder.class (obviously 
).
2. inside of the utils folder --> DefaultIviewPersonalization.class.
inside of the pagebuilder class you will find "handleEditMode" which is called in personalization.
if the iView inside of the page doesn't implement doEdit then it will go directly to the DefaultIviewPersonalization.
Hope this helps .
BR,
Saar