Working on an automated data handling system. It attempts to work out the format of the uploaded data itself but, if it fails, it asks the user to put in things like field delimiters so it can process the file properly.
Problem is that "tab" is a common field delimiter, so the text box for this needs to accept tab characters. This creates three problems.
1) The standard behaviour for a tab is to move on to the next form control. This is not a large form, so disabling doesn't create a large usability problem, but it will be very confusing for a minority of folk who are used to tabbing through a form by default.
2) Because of the above, users who don't tab through may still be unsure what to put in the box if the file is tab delimited. They may not think to try a tab character, even if we accept one.
3) If someone gets this far and puts a tab in the box, it will be very far from obvious that they have done so. The box will not display a visible character and will appear empty unless the user thinks to look for the position of the cursor.
Is there a better UX approach for this?