Hi
STRLIST is one option, but might be limited. Another option is to create several dialog boxes, which only differe in the visibility of some elements. Then use M2_BUTTON with conditoinal setRoot command in the callback action to jump to the one dialog, which has the intended visible elements. Note, that you can reuse elements (or complete element trees) in more than one dialog.
Then, finally, there is M2_HIDE(). I still did not document M2_HIDE, but i think there should be an example (HideS8Num).
https://code.google.com/p/m2tklib/source/browse/arduino/u8g/HideS8Num/HideS8Num.pde
Oliver