Which controls cannot be placed on an MDI Form?

Answer:

These controls cannot be placed on the MDI Form

1)Components :

example: BackgroundWorker,
ImageList,
HelpProvider,
Timer

2)Printing:
example: PrintDocument, PrintDialog

3)Dialogs
example: ColorDialog,
SaveFileDialog

These controls are placed in the Component Tray window.
It is the window below the Form window anad can be viewed in Design mode
It contains all the controls which cannot be viewed even by default
when the application executes.