Q:

How can I make an area where windows can be opened? C#

I'm working with C#. Basically I want to make an area inside of a form where other applications can be opened, but they can not be taken outside of the window. Much like how when opening multiple excel workbooks in one Excel application lets you move the workbooks around inside Excel, but not drag them to your desktop.
Any ideas on how to go about this? I've tried searching but I'm not sure how to describe this in a programmatic way.

A:

Multiple-Document Interface seems like what you might be going for.

Multiple-document interface (MDI) applications enable you to display
  multiple documents at the same time, with each document displayed in
  its own window. MDI applications often have a Window menu item with
  submenus for switching between windows or documents.

http://msdn.microsoft.com/en-us/library/xyhh2e7e(v=vs.110).aspx

