The reproducer from bug 746425 (https://bugzilla.redhat.com/attachment.cgi?id=530289 ) also works to reproduce this issue.

Hmm, Azureus started just fin on my F-17 vm. Which jvm are you using?

java-1.7.0-openjdk-1.7.0.3-2.1.fc17.1.x86_64

Do note the x86_64, I have a vague memory this was an issue in bug 746425...

I have just double checked using eclipse 4.2 (rawhide) and it works for me.

I have seen errors like this when I was trying to launch some program from within Eclipse, but the file that was to be opened was missing (f.e. deleted from command line). In this case, it is very likely that you azureus is passing to Program.launch incorrect arguments (specifically, a program that is not in the filesystem). 

This is exactly the same case as bug 746425 testcase. Alex, is there anything that can be done in SWT to show proper error message?

Changing the way SWT reports issues will be hard but it should never fallback to gnome24 calls nowadays on Fedora. I'll go through the code to find what might be causing it.

Not sure if this helps, but checking with jdb, it seems that the URL used in Program.launch was http://www.vuze.com:80/install/first.start?iid=&azid=C3DEY6WZYZI57ZUJADAKP24MZOMWH4TW&azv=4.7.0.2&locale=en&os.name=Linux

Actually the swt fallbacks on gnome24 in one of two cases:
(1) The desktop is actually gnome24, I do not expect this to be the case here.
(2) GIO launch fails - which imho is the case here.

This is the snippet:

package test;

import org.eclipse.swt.program.Program;
import org.eclipse.swt.widgets.Display;

public class Test {
	public static void main(String[] args) {
		Display display = new Display();
		boolean result = Program.launch("http://www.vuze.com:80/install/first.start?iid=&azid=C3DEY6WZYZI57ZUJADAKP24MZOMWH4TW&azv=4.7.0.2&locale=en&os.name=Linux");
		System.out.println(result);
	}

}

I can't make the snippet fail to me nor to reproduce it in any other way.
David, can you try with new user so we can be sure it's not some user config/cache?

If you start azureus locally on your computer running in a full gnome environment it works. At least a workaround...

So how you were starting it earlier?

For testing purpose, I created a minimal VM running F17 (or the beta at the time) and connected there by remote X.

*** Bug 882547 has been marked as a duplicate of this bug. ***

Just for reference - I have a patch series sent upstream that should help identifing/fixing this issue but they are waiting for some more reviews as Platform is a bit touchy place. 
https://bugs.eclipse.org/bugs/show_bug.cgi?id=376659

http://fedorapeople.org/cgit/akurtakov/public_git/eclipse.platform.swt.git/commit/?id=5527250a03712668daf31d8216bdea5f3d17fc4a is the one I think should fix the issue but we would see it only in eclipse 4.3(if approved) as I would not risk breaking local swt usage in anyway.

David, can you try on current rawhide ? My patchset is in and it should fix at least a few of the wrong fallbacks.

Still fails with the same error:

file:/usr/lib64/eclipse/plugins/org.eclipse.swt.gtk.linux.x86_64_3.101.0.v20130305-1021.jar ; file:/usr/bin/build-classpath ; file:/%20error ; file:/%20JVM_LIBDIR%20/usr/lib/jvm-exports/java-openjdk%20does%20not%20exist%20or%20is%20not%20a%20directory ; file:/usr/share/azureus/Azureus2.jar ; file:/
changeLocale: *Default Language* != English (United States). Searching without country..
changeLocale: Searching for language English in *any* country..
changeLocale: no message properties for Locale 'English (United States)' (en_US), using 'English (default)'
DEBUG::Mon Mar 11 22:08:19 CET 2013  Successfully migrated key management

(Vuze:2452): Pango-WARNING **: failed to choose a font, expect ugly output. engine-type='PangoRenderFc', script='common'
java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
	at org.gudy.azureus2.ui.swt.Main.<init>(Main.java:114)
	at org.gudy.azureus2.ui.swt.Main.main(Main.java:292)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:601)
	at com.aelitis.azureus.launcher.MainExecutor$1.run(MainExecutor.java:37)
	at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: 
	no swt-gnome-gtk-4320 in java.library.path
	no swt-gnome-gtk in java.library.path
	Can't load library: /home/me/.swt/lib/linux/x86_64/libswt-gnome-gtk-4320.so
	Can't load library: /home/me/.swt/lib/linux/x86_64/libswt-gnome-gtk.so

	at org.eclipse.swt.internal.Library.loadLibrary(Library.java:331)
	at org.eclipse.swt.internal.Library.loadLibrary(Library.java:240)
	at org.eclipse.swt.internal.gnome.GNOME.<clinit>(GNOME.java:21)
	at org.eclipse.swt.program.Program.gnome_launch(Program.java:388)
	at org.eclipse.swt.program.Program.launch(Program.java:983)
	at org.eclipse.swt.program.Program.launch(Program.java:939)
	at org.gudy.azureus2.ui.swt.Utils.launch(Utils.java:1033)
	at com.aelitis.azureus.ui.swt.Initializer.checkInstallID(Initializer.java:305)
	at com.aelitis.azureus.ui.swt.Initializer.runInSWTThread(Initializer.java:274)
	at org.gudy.azureus2.ui.swt.mainwindow.SWTThread.<init>(SWTThread.java:229)
	at org.gudy.azureus2.ui.swt.mainwindow.SWTThread.createInstance(SWTThread.java:63)
	at com.aelitis.azureus.ui.swt.Initializer.<init>(Initializer.java:164)
	... 12 more

eclipse-swt-4.3.0-0.24.git3fd9eca.fc19.x86_64
azureus-4.8.1.2-3.fc19.noarch

Resetting to rawhide for further investigation.

This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle.
Changing version to '19'.

(As we did not run this process for some time, it could affect also pre-Fedora 19 development
cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.)

More information and reason for this action is here:
https://fedoraproject.org/wiki/BugZappers/HouseKeeping/Fedora19

This bug is fixed for me in Fedora 19 + updates-testing (Azureus works fine)

Making as closed worksforme per comment 19.