Bug 8581 Switch J Search to StructuredContentProvider
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/search/FindImplementorsAction.java
public FindImplementorsAction() {
		super(SearchMessages.getString("Search.FindImplementorsAction.label"), new Class[] {IType.class}); 
		setToolTipText(SearchMessages.getString("Search.FindImplementorsAction.tooltip")); 
		setImageDescriptor(JavaPluginImages.DESC_OBJS_SEARCH_DECL);
	}
	public boolean canOperateOn(ISelection sel) {
		if (!super.canOperateOn(sel))
			return false;
		IJavaElement element= getJavaElement(sel, true);
		if (element.getElementType() == IJavaElement.TYPE)
			try {
				return ((IType) element).isInterface();
			} catch (JavaModelException ex) {
				ExceptionHandler.log(ex, SearchMessages.getString("Search.Error.javaElementAccess.message")); 
				return false;
			}
		
		return false;
	}
	protected int getLimitTo() {
		return IJavaSearchConstants.IMPLEMENTORS;
	}
}