Ah, so because button's text is not the value it doesn't get kept, however a field's text is a value so field text does get kept? Thanks for clarification and the snippet!
Just to be clear, a field's .value attribute, which is represented as a rich text table, is the complete, underlying contents stored in the field. Fields have .text, .images, and .data attributes which can be read and written, but all three are alternate views/subsets of the same contents (as a plain-text string, as a list of inline images, and as encoded/decoded LOVE data, respectively), as scripting conveniences.
Buttons have a .value attribute as well, but it represents the boolean (1/0) value of checkboxes, and has no relationship to the .text attribute of the button, which controls the button's label.
Sliders have a .value attribute which corresponds to their numerical value, and Grids have a .value attribute which corresponds to the table data they contain.