Windows sends the window that contains the mouse cursor the WM_SETCURSOR message, giving it an opportunity to change the cursor shape. A control like TextBox takes advantage of that, changing the cursor into a I-bar. The Control.Cursor property determines what shape will be used.
The Cursor.Current property changes the shape directly, without waiting for a WM_SETCURSOR response. In most cases, that shape is unlikely to survive for long. As soon as the user moves the mouse, WM_SETCURSOR changes it back to Control.Cursor.
The UseWaitCursor property was added in .NET 2.0 to make it easier to display an hourglass. Unfortunately, it doesn’t work very well. It requires a WM_SETCURSOR message to change the shape and that won’t happen when you set the property to true and then do something that takes a while. Try this code for example:
private void button1_Click(object sender, EventArgs e) {
this.UseWaitCursor = true;
System.Threading.Thread.Sleep(3000);
this.UseWaitCursor = false;
}
The cursor never changes. To whack that into shape, you’ll need to use Cursor.Current as well. Here is a little helper class to make it easy:
using System;
using System.Windows.Forms;
public class HourGlass : IDisposable {
public HourGlass() {
Enabled = true;
}
public void Dispose() {
Enabled = false;
}
public static bool Enabled {
get { return Application.UseWaitCursor; }
set {
if (value == Application.UseWaitCursor) return;
Application.UseWaitCursor = value;
Form f = Form.ActiveForm;
if (f != null && f.Handle != IntPtr.Zero) // Send WM_SETCURSOR
SendMessage(f.Handle, 0x20, f.Handle, (IntPtr)1);
}
}
[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);
}
And use it like this:
private void button1_Click(object sender, EventArgs e) {
using (new HourGlass()) {
System.Threading.Thread.Sleep(3000);
}
}