Improving the Java AST debugging view.

[jlahoda]

The AST debug view for Java (java/java.debug) has some trouble:

• it has hardcoded all AST node kinds, so if a new AST node kind is added, it needs an update
• the highlight showing the current AST node's span is not cleared when the view is unselected
• the highlight color is really ugly

This patch attempts to improve these aspects.

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[mbien]

how can I use the debugging module? Build it separately and install it in the IDE?

[jlahoda]

In Navigator for Java source files, there should be a few debugging panels, like Trees (NetBeans Development), which this patch is updating. This is part of the standard build, but is only enabled when assertions are enabled, or -J-Dorg.netbeans.modules.java.debug.enable=true command line option is used.

[mbien]

code makes sense to me as far as I can tell. It works also as advertised.

learned something new, this certainly is a useful tool to debug some editor features.

lets get this in - should be low risk anyway since this is not enabled by default..