Degrade ADT in Eclipse

If you would like to work on an low version ADT, you may degrade your ADT.

Eclipse->Help->About Eclipse Platform->Installation Details->Unstall all Android relevant items

Download ADT for your SDK version.

Install ADT as the offline mode.

It's OK.

If a project is created with the error proguard.cfg (No such file or directory), you may copy the 'proguard.cfg' in the Android source project to the asked path.