Modelio 3.x, 4.x

In a fresh installation (unpacked the zipped binaries) on Debian testing, I experience the following problem:

Opening e.g. the classes of a project fails with this error message:

org.eclipse.swt.SWTException: Failed to execute runnable (org.eclipse.e4.core.di.InjectionException: org.eclipse.swt.SWTError: No more handles [MOZILLA_FIVE_HOME='/usr/bin/firefox'](java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: 
    /home/daniel/.eclipse/1404645758_linux_gtk_x86_64/configuration/org.eclipse.osgi/168/0/.cp/libswt-mozilla-gtk-4430.so: libxpcom.so: cannot open shared object file: No such file or directory
    no swt-mozilla-gtk in java.library.path
    /home/daniel/.swt/lib/linux/x86_64/libswt-mozilla-gtk-4430.so: libxpcom.so: cannot open shared object file: No such file or directory
    Can't load library: /home/daniel/.swt/lib/linux/x86_64/libswt-mozilla-gtk.so
))
Failed to execute runnable (org.eclipse.e4.core.di.InjectionException: org.eclipse.swt.SWTError: No more handles [MOZILLA_FIVE_HOME='/usr/bin/firefox'] (java.lang.UnsatisfiedLinkError: Could not load SWT library. Reasons: 
    /home/daniel/.eclipse/1404645758_linux_gtk_x86_64/configuration/org.eclipse.osgi/168/0/.cp/libswt-mozilla-gtk-4430.so: libxpcom.so: cannot open shared object file: No such file or directory
    no swt-mozilla-gtk in java.library.path
    /home/daniel/.swt/lib/linux/x86_64/libswt-mozilla-gtk-4430.so: libxpcom.so: cannot open shared object file: No such file or directory
    Can't load library: /home/daniel/.swt/lib/linux/x86_64/libswt-mozilla-gtk.so
))

Further investigation shows that libxpcom.so seems to be missing in current versions of Firefox, iirc the Mozilla people say that libxul should be used instead.