Watermark in System.Windows.Forms.TextBox
lately I needed a watermark textbox, the first thing that popped in to my head was OnLeave and OnEnter events of textbox, but first I googled it and I got two links first was the one in CodeProject which used the System.Drawing namespace and the other one was here using the SendMessage() over here http://vidmar.net/weblog/archive/2008/11/05/watermarked-textbox-in-windows-forms-on-.net.aspx.
I beleive the SendMessage one is much easier and it also has no flickering in it. though I used it.
I hope it will be helpful for you.