C# Windows Forms - SendMessage EM_SETCUEBANNER on textbox not working

Question

I'm making an application in C# with windows forms. I want to have a placeholder for my textboxes and I found the method of SendMessage from User32.dll. Here's my code (placed in LoginForm.cs which is one of the first forms if settings file doesn't exist):

private const int EM_SETCUEBANNER = 0x1501;

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    private static extern Int32 SendMessage(IntPtr hWnd, int msg, int wParam, [MarshalAs(UnmanagedType.LPWStr)]string lParam);

Is placed inside the class. As my constructor I got:

public LoginForm()
{
    InitializeComponent();

    SendMessage(hostname.Handle, EM_SETCUEBANNER, 0, "Hostname");
    SendMessage(port.Handle, EM_SETCUEBANNER, 0, "Port");
    SendMessage(username.Handle, EM_SETCUEBANNER, 0, "Username");
    SendMessage(password.Handle, EM_SETCUEBANNER, 0, "Password");
    SendMessage(database.Handle, EM_SETCUEBANNER, 0, "Database");
}

My hostname , port , username , password , database are all textboxes. But if I run my application, it doesn't apply the placeholders, it simply focuses on the last textbox.

What am I doing wrong? I get no errors.

Answer 1

I was dumb, I forgot to add Application.EnableVisualStyles(); to my Program.cs.