For me on Ubuntu 24, the text editor fails to show anything, showing error:

org.eclipse.core.runtime.CoreException: Plug-in "org.eclipse.dltk.ruby.ui" was unable to instantiate class "org.eclipse.dltk.ruby.internal.ui.editor.RubyEditor".
    at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.throwException(RegistryStrategyOSGI.java:242)

(and many hundreds of lines more, similar to this). I have downloaded the All-in-One DLTK SDK - includes binaries and source code of DLTK Core Frameworks, Ruby IDE and TCL IDE for Eclipse Platform 3.3 package (https://www.eclipse.org/dltk/downloads.php), and copied and pasted the files from the plugins and features folders to the ones of my eclipse directory.

When I also install the DLTK from Help->Install new software (all three), the script explorer shows my project folder and I can generate Ruby files etc., but I cannot configure the interpreter any more, getting this error message:

Unable to create the selected preference page.
org/eclipse/dltk/internal/debug/ui/interpreters/InterpreterPreferencePage 

My Ruby interpreter is set to usr/bin/ruby, which is what comes up for which ruby in my terminal.

Does anybody know how I could resolve my setup ?