[news.eclipse.tools] How can I insert a string into an editor with an ex

[lge@xxxxxxxxxx (Leen Geeraerts)]

Hi!

I am in the process of writing a plug-in to enter a simple string into the
active editor. 
This action should take place if I click on a certain menu-item from a
pulldownmenu in my toolbar. 
I can perform simple actions according to each menu, but now I want to be
able to insert a specific string (different for each menu-item) into the
active editor.
I guess I need to work with IDocument to be able to do this, but i cannot
find a way to reach the active IDocument from the workbench.

Thanks for looking into this!
Kind regards,
Leen