First a summary of the questions, and then the detail...
* Do you recommend immediate feedback on error status icons in table rows, or instead not changing them until a Save button is pressed?
* Can you point me to any good examples of this immediate feedback in publicly available web apps?
* Can you point me to any good references, online or otherwise, describing user interface design best practices?
Now the detail:
I have a data table displayed on a web page. The web framework is Apache Wicket, but that's not really relevant to the question, except that for now I'll be using Wicket tables and not all-Javascript tables.
Each row has an error icon that appears if there is an error condition in any cell in that row, or an error in relationships of cells in that row (for example a value whose required status is conditional on the value in another cell in that row).
My opinion is that the visibility of the error icon should accurately reflect the error status of the row at any point in time. It should disappear as soon as all errors are corrected, and appear as soon as an error is introduced. I also have tooltips on the error icon containing all error messages applicable to that row.
My colleague, who has considerable influence over the design, says she has never seen an application that had this immediate feedback, and is not comfortable with this approach. I think she feels the changing visibility of the icons would be a distraction. Instead, she prefers that they not be visible at all until the user presses the Save button; at that time all rows with errors get the error icon; and regardless of subsequent changes to data in the table, the error icons' visibility would not change until the Save button is pressed.
My position is that this is not helpful to the user, who can only rely on the correctness of the error icons some of the time. The save button becomes a validate button as well, and when the errors are all fixed, pressing it moves on to the next panel -- not necessarily what the user wanted.
Given this, do you have any ideas about my questions above?
I have seen what you are talking about. for instace when you create an account. as you type a password you see the strength of the password. for a secure site that require a strong password it would make sense to flag as they are typing or before they hit submit.
another example is a fantasy basketball site that takes cap figures when you draft. it lets me know before i hit save/send/submit that its not valid, so i can correct before and save everyone time.
my advice is humor your colleague superior and do it both ways, so she can compare. or show the client both ways. if validation is done additionally client side regardless it shouldn't be much work to continue both ways.
make sure validation is done server side as well. because people can inject html/javascript via their browser.