In a another comment I reminded about the same fact; the keyboard cannot slide out more than 70%... If you drop the phone, the strain would be really powerful and might break the sliding rails or the "sticks". Or perhaps the fixing between the phone and the OH would open; could it be made intentionally "weak": the OH would become loose if the phone+OH is dropped. But would the strain on the interfacing connector then be too powerful? Anyway, according to the photo in my previous comment, Samsung made a Qwerty which slides out about 70%.