...replace blanks in a string with typed characters?

I have a text object (txt_fact) displaying a sentence that includes one word replaced with a line of blanks. I want the user to be able to replace the blanks with the missing word, or at least write on top of the blanks.

Currently I use the following method:

1. Add a second text object (txt_answer) that sits over the blanks in txt_fact.

2. Add a textbox object with the CSS set to render it invisible.

3. Focus the textbox and set txt_answer to display whatever text is typed into the textbox.

This would work fine, except fonts in a text object display differently depending upon the browser/device, so I can't guarantee that the position of txt_answer will always lie precisely over the blanks.

Is it possible to derive the coordinates of characters in a string? e.g. find x,y for the 3rd "_" in "I laughed at the _______ dog."

Failing that, is this something I can handle with regex? I figured I might be able to use a replace expression, but I'm unsure how to handle the user deleting characters that have been added once the blanks have been replaced.

Or maybe there is another way?

Finding screen coordinates for a character in Text object is almost impossible, because browsers render text differently. You can do it with SpriteFont, but this will still be a difficult task.

I suggest using find() expression to search for the first "_" character. If player types the correct letter, replace this "_" with the letter:

Set n to find(MyText, "_")
Set MyText to left(MyText, n) & TypedLetter & right(MyText, len(MyText)-n-1)