launcher tabs code reuse

Hello,

I'm developing a Henshin Concurrent Engine for gemoc with @szschaler. My code aims to reuse as much as possible of the existing concurrent engine code base. I've noticed that when it comes to different launcher tabs there was a lot of code we had to copy instead of inherit/directly use it as the plugin does not export it. Would it be possible to make that part more reusable in the future?

[our tabs](https://github.com/szschaler/henshin_xdsmls/tree/master/uk.ac.kcl.inf.modelling.xdsml.gemoc_henshin/src/uk/ac/kcl/inf/modelling/xdsml/gemoc_henshin/engine/ui/launcher/tabs)

Thank you,
Kinga