There was a typing error in the download runtime url.
I have fixed it in the trunk.
Attached is a patch - jbide-11683c.patch.

You can test as follows:

add -Djboss.runtime.directory.url=http://download.jboss.org/jbosstools/examples/download_runtimes.xml to the VM arguments
and you will get JBoss Seam 2.3.0 Beta1 in the Runtimes dialog

create the following file in your file system

<runtimes>
	<runtime
            id="org.jboss.tools.runtime.core.seam.230" 
            name="JBoss Seam 2.3.0.Beta2"
            version="2.3.0.Beta2"
            size="115.4MB"
			url="http://sourceforge.net/projects/jboss/files/JBoss%20Seam/2.3.0.Beta2/jboss-seam-2.3.0.Beta2-dist.zip/?use_mirror=autoselect"
            disclaimer="true"/>
</runtimes>

add -Djboss.runtime.directory.url=file:///<your_file> to the VM arguments

You will get JBoss Seam 2.3.0 Beta2 in the Runtimes dialog

runtime detection preference page has a download button. (warning: ui is not pretty)

The Runtimes dialog is a simple dialog that shows a list of runtimes that can be downloaded. There is no any validation, only the user need to do is to choose a runtime and click the OK button.
What would you like me to change in the UI?

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