Thank you for that idea but it doesn't really solve the problem. With your suggestion the thick border only appears after the user single-clicks twice in succession on a listbox item.
To accomplish the thick border outline I just need to add this to my styles.css file:
However, whether I try what's shown above or your suggestion, it doesn't solve the larger problem. Let me demonstrate through three screenshots. Notice in the 2nd & 3rd screenshots that the original colouring of the RadListBoxItem has turned to grey. That's what I want to avoid but can't figure out how.
Incidentally, I'm assigning the custom background colour in the RadListBox's "ItemCreated" event handler. There are 3 possibilities:
// Green gradient
// Pink gradient
// Orange gradient
So, to be clear, what I'm trying to figure out how to do is to maintain these custom gradient backgrounds after a RadListBoxItem has been clicked upon. Yes, I will thicken the border to indicate which is the current one but I don't want the original colourful gradient to turn grey.
How do I do that?