startup edit works only when run from ide

Hello,

I've been playing around building NetBeans and although what I'm doing 
is all kind of silly, still I would like to figure it out, I'm at a bit 
of a loss and was hoping someone might shed some light on my predicament.

There seems to be a bug in the Nimbus LnF implementation or maybe its 
the JRE but after java version 1.8.0_51 on large files after reaching a 
minimum size the scroll bar thumbs disappear, they still work but kind 
of hard to find when they can't be seen.  There is a workaround setting 
the minimum size of the thumb in the UIDefaults dictionary which I've 
added into org.netbeans.core.startup.Main.main after checking for Nimbus 
LnF:

javax.swing.UIManager.getLookAndFeel().getDefaults().put("ScrollBar.minimumThumbSize", 
new java.awt.Dimension(30, 30));

For better or for worse but it does work if I run the Startup module 
from a running instance of NetBeans.  If I run my built 
netbeans/bin/netbeans directly it does not.

Why?

-- Mark