We have a textbox that the user enters sets of terms into, delimited by commas and separated by newlines. There may be thousands of valid terms, so we'd like to offer the user intellisense-style suggestions as they type. The default autocomplete isn't adequate because it will only do prefix-matching on the entire textbox, and won't support multiline textboxes. How do I implement intellisense-like suggestion boxes for a winforms textbox?
I wrote this article back in 2005 about doing intellisense with a listbox and a textbox control (or it might have been a RTB). It's far from polished or perfect but might get you started.
I do exactly that using the Infragistics UltraCombo component. Unfortunately it's not free.
来源：https://stackoverflow.com/questions/767622/how-do-i-implement-intellisense-like-suggestion-boxes-for-a-winforms-textbox