@Override
protected ConfigurableCompletionProvider doCreateProposal(String proposal, StyledString displayString, Image image, int priority, context){

ConfigurationCompletionProvider theProposal = super.doCreateProposal(proposal,
displayString, image, priority, context);

theProposal.setAdditionalProposalInfo("functionDocumentation");

}

Greeting :
'module' name=ID '{'
innerElements += ModuleInnerElements*
'}'
;

ModuleInnerElements:
      Functions
      | OtherStuff
      | OtherStuff
      | OtherStuff
      | OtherStuff
;

Functions:
     (GuiStart | GuiAddRow | GuiEnd) FunctionImplementation
;

GuiStart:
     'guiStart';
;

GuiAddRow:
     'guiAddRow';
;

GuiEnd:
     'guiEnd';
;

	@Override
	public void completeKeyword(Keyword keyword, ContentAssistContext contentAssistContext,
			ICompletionProposalAcceptor acceptor) {
		ICompletionProposal proposal = createCompletionProposal(keyword.getValue(), getKeywordDisplayString(keyword),
				getImage(keyword), contentAssistContext);
//do a downcast here and add the infos you need
		getPriorityHelper().adjustKeywordPriority(proposal, contentAssistContext.getPrefix());
		acceptor.accept(proposal);
	}