1. Decker supports a limited set of unicode characters within text, and unrecognized characters are turned into character 255, "UNKNOWN", upon ingestion. You can, however, very easily customize how this character appears in a given font using the font editor. (The font editor is part of a larger deck All About Fonts that contains a variety of other notes you might find useful).
2. It isn't possible to use a different font within a field exclusively while text is highlighted, but you could certainly make intentionally illegible custom fonts that could still be copied to the clipboard as ordinary text. This would be mechanically a bit different, but might still preserve a similar idea. Perhaps there could be some affordance within the game for giving a player a "scratchpad" field they can paste into? You could alternatively build a contraption of some kind which encapsulates swapping out the font of a field when it is clicked, but it would be difficult to provide this kind of behavior on a granular level and still permit selection. In a locked field, links could be used to trigger arbitrary scripts when particular text fragments are clicked, but they do have a recognizable visual appearance: a dotted underline.
3. You cannot select text within a locked field, but there are a few subtle consequences of how field and text patterns work which might allow you to accomplish something similar to what you're describing:
- A transparent field on top of a black background (with text in the default pattern 1) will appear to be invisible until it is selected, in which case it will appear white.
- If you change the pattern of a span of text within a "rich text" field to white (rather than changing the default pattern for the entire field), it will appear to be invisible until it is selected, in which case it will appear white within a black selection highlight.
As a general note, some of the limitations of text and selections within Decker are a consequence of its approach to ensuring that fields are usable on keyboardless devices like tablets. The "touch input" mode (which can be manually enabled via the Decker menu) will interfere with some kinds of nasty text obfuscation tricks.






