Subclass NativeWindow
using System;
using System.Drawing;
using System.Windows.Forms;
class CaptureLoss: Form
{
public static void Main()
{
Application.Run(new CaptureLoss());
}
public CaptureLoss()
{
Text = "Capture Loss";
CaptureLossWindow win = new CaptureLossWindow();
win.form = this;
win.AssignHandle(Handle);
}
protected override void OnMouseDown(MouseEventArgs mea)
{
Invalidate();
}
public void OnLostCapture()
{
Invalidate();
}
protected override void OnPaint(PaintEventArgs pea)
{
Graphics grfx = pea.Graphics;
if (Capture)
grfx.FillRectangle(Brushes.Red, ClientRectangle);
else
grfx.FillRectangle(Brushes.Gray, ClientRectangle);
}
}
class CaptureLossWindow : NativeWindow
{
public CaptureLoss form;
protected override void WndProc(ref Message message)
{
if (message.Msg == 533) // WM_CAPTURECHANGED
form.OnLostCapture();
base.WndProc(ref message);
}
}
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