Q:

Android project does not rebuild after modifying underlying Java project

I have an Android project (A) that depends upon a Java-only project (B) in Eclipse.  To be specific, in the Project properties of (A), Java Build Path->Projects, (B) is listed as a required project on the build path. 
When I edit source files in (B) and then save, then run the Android project, I get the following warning in the Console:
ActivityManager: Warning: Activity not started, its current task has been brought to the front

The root problem seems to be that the .apk file is not getting rebuilt.   E.g. it was last modified at November 8, 2012 1:46:41 PM, then I made a change in B and saved.   The timestamp remains the same. 
To work around the problem, I can modify a file in (A).  Interestingly, after saving, the .apk is still not updated!   (I have "Build automatically" enabled).   But when I run the Android project, it forces the .apk to be rebuilt and then my changes to (B) get propagated to the .apk file. 
I believe this used to work with an earlier version of ADT, but I'm not sure when it stopped working.   I'm currently using Eclipse 4.2.1 (Juno) with Android Development Toolkit Version: 20.0.3.v201208082019-427395
Is there something possibly missing in my project setup?   Or is this an ADT bug? 

A:

This is fixed in the r21 version of the Android SDK tools.