Zoom (setViewPosition) not working for java 1.4.2

Question

I created a JScollPane with a RenderableDisplay.
I programmed a zoom function by adding a mouse
listener to the RenderableDisplay. Right click..
zoom in..left click..zoom out.
All works fine with java 1.3.X. Nothing happens
with java 1.4.X. I traced the problem to the setViewPosition method of the JViewport class.
I unzipped the source and found the following
differences in the setViewPosition routines..
Java 1.3.04
     //Force a repaint of the whole component
//on the next call to paint
repaintAll = windowBlitPaint(g);
Java 1.4.X
     //Repaint the complete component if the blit
//succeeded and needsRepaintAfterBlit returns true
repaintAll = (WindowBlitPaint(g) && needsRepaintAfterBlit())
I unjared dt.jar and went to change the 1.4 source
to match the 1.3.04 code. I recompiled and rejared and
placed the new dt.jar in lib and made sure my CLASSPATH
pointed there. When I went to recompile my source code
that referenced the setViewPosition method I got:
/JAVA/j2sdk1.4.2_01/lib/dt.jar(javax/swing/UIManager.java):90: class UIManager is public, should be declared in a file named UIManager.java
..and similar messages for each file under javax/swing
I first need to be able to recompile the swing with
a change to JViewport.java and see if the old code
would fix my problem. I recreated dt.jar but for
some reason putting that in my CLASSPATH doesn't work.
(as mentioned with error above). Does anyone know
what I need to do to avoid the above compile errors?
Second, I need to figure why the code needsRepaintAfterBlit() is returning false for my application.
Any help will be appreciated...

Answer 1

Well, in order to "investigate whey the "needsRepaintAfterBlit()" method is apparently coming out false " I need to run my program in debug. In
order to look at values at breakpoints in a debugger
I need to compile with debug on...which gets me back
to my very first problem of needing to recompile the
swing.
I found the solution was to change the JViewport.java
in the jre/lib/rt.jar and then run.