Holding a button (tile) should display 6 further tiles around the tile pressed and with the move on that tile the action on that tile should happen.
I'm sure its easier having the further functions displayed right away. For example capital, special characters, ÄÖÜ, no switch to the numeric/special character layout should be necessary. The further functions must be shown in the main tile, just smaller and more transparent. No additional visible number row is necessary if the numbers are further functions of buttons W E T Z I O. If you do have further questions do not hesitate to contact me ;)