Calculate 'textheight' of RichtextBox

Hello,

I need to have a richtextbox fit to text. In other words I need to calculate it's height to adjust according to how much text is in it.

The RTB will have different font sizes in it. -So it isn't just a matter of getting the lines and multiply it by Form1.FontSize("X") .

I have made a project (see attachement 4.zip / 3kB). It uses the richtextbox scrollbar (and GetScrollInfo -API) to calculate the textheight.

The sample project works. But it needs a scrollbar, in other words the scrollbar must be visible.

I need any ideas on how to get the textheight of a RTB by a better method, if this metod exists.