[System.Runtime.InteropServices.DllImport("gdi32.dll")]
private static extern IntPtr CreateRectRgn(int X1, int Y1, int X2, int Y2);
[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern IntPtr SetWindowRgn(IntPtr hwnd, IntPtr hRgn, bool bRedraw);
[System.Runtime.InteropServices.DllImport("gdi32.dll")]
private static extern IntPtr DeleteObject(IntPtr hObject);
private static void RemoveControlBorder(System.Windows.Forms.Control Ctrl, int BorderSize) {
IntPtr Rgn = CreateRectRgn(BorderSize, BorderSize, Ctrl.Width - BorderSize, Ctrl.Height - BorderSize); SetWindowRgn(Ctrl.Handle, Rgn,
true);
DeleteObject(Rgn);
}
private void Form1_Load(object sender, EventArgs e) {
RemoveControlBorder(this.button1, 3);
}