WHY! doesn't this dispose of all the objects on the flow panel!?

Question

WHY! doesn't this dispose of all the objects on the flow panel!? the count shows 5 and there are 5 buttonsWithProperties on the form, no other objects are on the form.

foreach (ButtonWithProperties itemButton in flowLayoutPanel1.Controls)
        {
            itemButton.Dispose();
        }

It disposes 3 of the object but not the last 2...

Answer 1

Indeed it's a bad practice to Dispose() an object to which there is a live reference (in your visual tree). If you want to remove the buttons, you perhaps have to remove them from Controls in an orderly way. See http://msdn.microsoft.com/en-us/library/system.windows.forms.control.controlcollection.removeat.aspx.

Edit:
Please note that the button is an IDisposable, therefore the version with RemoveAt needs an explicit Dispose:

var controls = flowLayoutPanel1.Controls;
for (int i = controls.Count - 1; i >= 0; --i)
{
    var c = controls[i];
    if (c is ButtonWithProperties)
    {
        flowLayoutPanel1.Controls.RemoveAt(i);
        c.Dispose();
    }
}

Edit:
The documentation suggests that Dispose should be called even if one is using Clear. So if you don't need the buttons any more, you should Dispose() them.