Custom properties on a win32 window

I've heard (well read, at http://www.ddj.com/windows/184416861), that i开发者_JAVA技巧t's possible to set custom properties on a Win32 window.

The trouble is, the download for the article above is on an ftp server that won't let me in.

As a bit of background info, I have a .NET app. The main window is registered to handle custom window messages. From a separate app, I need to post messages to this window. I can't find the window by caption as the caption changes. I can't find it JUST by window class, as the window class is the same for all forms in that app domain.

Ideally, I'd like to set a custom property on the Win32 window of the main form (Form1) that say, yes, this is form1. Then when I'm enumerating the windows of this app, I can tell that this is the required form by seeing if this custom property exists.

Cheers,

Steve

See here for an overview of window properties. Basically, you call the Win32 API function SetProp to set a window property and GetProp to retrieve it. There are a few more functions for enumerating properties and the like, but it sounds as if SetProp and GetProp is all you need.

As Martin says, the answer is the Win32 APIs GetProp and SetProp.

Here's what I now do when I create the main form:

[DllImport("user32.dll", SetLastError=true)]
static extern bool SetProp(IntPtr hWnd, string lpString, IntPtr hData);

SetProp( this.Handle, @"foo", new IntPtr( 1 ) ) ;

Now, I can check this property when enumerating the windows:

[DllImport("user32.dll")]
private static extern IntPtr GetProp(IntPtr hWnd, string lpString);

IntPtr result = GetProp( (IntPtr) hWnd, @"foo" ) ;