I have been using Tec 7 for 4 years. It is a solvent free mastic and adhesive and can be used to bond most items. It is a sealant for all sorts of bathroom areas and is excellent to seal around window frames, coving and more. And it never cracks open. It is more expensive than ordinary mastic but you do the job once and it last! Buy it!
This is an excellent book that covers all German grammar basics - a must for beginners and intermediates. Highly recommended! love the colour coding which really does help to understand parts of the subject being described.