Delphi MDI Form

Imagine an MDI application where the MDIFrame has many MDIChild forms?each one derived from TBlueForm class. The TBlueForm class has a public method named ChangeColor which only makes the form’s color change from gray to blue. How do I call the ChangeColor method from the MDIFrame without referencing the Childform’s name but using the ActiveMDIChild property of the MDIFrame?


When I tried this, the compiler returned the error:

          Undeclared identifier:'ChangeColor'

So it seems that ActiveMDIChild only recognizes the methods inherited of TForm. All the MDIChild forms were included in the uses session of the MDIFrame.

You could try typecasting the ActiveMDIChild like so:


This code should work.

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