You want a PictureBox to be transparent and show the form's background where the picture box image doesn't cover...

import dfl.all;
import dfl.internal.winapi;

/// A simple picture box with a transparent background and does not accept mouse or click events.
class SimplePictureBox: PictureBox
{
        protected override void onPaintBackground(PaintEventArgs ea)
        {
        }


        protected override void createParams(inout CreateParams cp)
        {
                super.createParams(cp);
                cp.exStyle |= WS_EX_TRANSPARENT;
        }
}

ou can even use this in Entice Designer by adding a regular PictureBox to your form, right-clicking it, going into the Properties, and changing the type to SimplePictureBox.