How display a Model form in a position relative to the a control in the parent window (opener)

Question

well i have a form that i open using ShowDialog(this).
i try to change the position of the form using its Location property, but i dont understand this position is relative to what exactly?
i want to open this form below a certain button. so how can this be done? thanks

Answer 1

A Form will expect the co-ordinates relative to the screen’s top-left corner. However, the location of a Control within a Form is relative to the top-left corner of the form^†.

Use the Control’s Location property to find its location, and then call PointToScreen on the Form object to turn it into screen co-ordinates. Then you can position the new form relative to that.

For example:

var locationInForm = myControl.Location;
var locationOnScreen = mainForm.PointToScreen(locationInForm);

using (var model = new ModelForm())
{
    model.Location = locationOnScreen + myControl.Height + 3;
    model.ShowDialog();
}

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^† Actually the top-left corner of the client area of the form.