How to determine the height of an InputBox?

I'm using the InputBox from the VB .dll. When I display it, I want to put it in a particular place relative to the controls it will have an impact on (out of their way). So I have this pseudocode for showing the InputBox ("selectionStart" is a Point assigned to on MouseDown):

int HeightOfInputBox = ? <- What is this value?
 int XPos = selectionStart.X;
 int YPos = selectionStart.Y - HeightOfInputBox; 
 Interaction.InputBox("Prompt", "Title", "DefaultResponse", XPos, YPos);
 

My question is: What is the height of an InputBox?

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