I had to deal with the annoying flickering-textbox problem yesterday. When I had to deal with this previously, I used a Windows Control that I got from a sample application at some point. But as I like to know everything, I googled for a solution to this problem that I could understand.
Here's one easy way to get your textbox to stop flickering: We're going to call the Win32 API function
LockWindowUpdate before making any changes to the text in the textbox.
This function is found in the
User32 dll, so we need to import it:
public static extern bool LockWindowUpdate(System.IntPtr hWndLock);
One thing to note is that you can only lock one window at a time. That means that if someone else has a window locked, then you can't lock this one. It also means that someone else can lock a window, which means that your window gets unlocked and therefore your textbox will flicker. There's a solution, found at the same site I found this one; look at the update.
Original article here