Selecting font hight from within a program

[cahlucas]

(11-13-2020 03:15 PM)Joe Horn Wrote:  See the built-in Help screen about the STRING function. It has an optional argument which allows you to control the font size, with more font options than just the usual three.

Dear Mr. Horn,
What I can tell from the help function is that it is mainly intended for formatting numbers. What I need is a function to place preset size letters and digits anywhere on the screen. Also, a black square must be placed in a single variable spot, which acts as a cursor, such that the digit below it is displayed as white transparent (like GXOR on the HP-50g). I don't know if that will be with the STRING function, and if it can, I don't know how. Maybe you can put me on the right path. I hope to hear from you soon. Sincerely, Karel.