You're question doesn't make any sense. There is no "attach"ing a Form class. I have no idea what you're trying to do or describe. A guide to posting questions on CodeProject[^] Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic      2006, 2007, 2008

This doesn't work because you created a normal (nothing on it) instance of a Form class. If you already have a form defined, you should be creating an instace of THAT form, not System.Windows.Form. A guide to posting questions on CodeProject[^] Dave Kreskowiak Microsoft MVP Visual Developer - Visual Basic      2006, 2007, 2008

You could show that "Form" in the windows menu by programatically adding it to the menu via something like... WindowsMenu.DropDownItems.Add("Whatever") I am not sure you can get it to show up as part of your MdiWindowList but you can try with something like... MenuStrip.MdiWindowListItem.DropDownItems.Add("Whatever") In both cases you would have to handle the DropDownItemClicked event for that menu item programatically to set focus to the "Form" if that menu item was clicked. You would also want to delete the menu item programatically when the "Form" was closed.

Thank you for your reply . I tried it but an error displayed System.Reflection.TargetInvocationException was unhandled again I want to clear it I want to call a public sub declared inside the form class which I am opening through assembly Hope to clear it for me