>I'm drawing a blank on this feature where like a textbox or some other text control has too much text and by setting this magical control property it looks like a tooltiptext by extending the text display beyond the control?
I think we had a class posted around here, ages ago, borderless form which would appear on top of your control and look like a tooltip, and would disappear on its own .MouseLeave() event. Your .tooltiptext would have to be "=thisform.ShowToolForm(this)" and the ShowToolForm method should return a "" (because that's expected of an expression in the tooltiptext property).
Or some trick like that. You could likewise do that in your controls .mouseEnter or .gotFocus. IIRC, the code was actually quite short, the form and the scaffolding to call it were below forty lines altogether.