Passing variables from main form to input form

Question

I have a simple question. I have a main form, and then a startup form from where I can select a new 3D model to generate. When selecting a new 3D model from the startup form

Answer 1

Add a public property on your main form

public bool IsDirty
{
    get;set;
}

you can then access this.ParentForm.IsDirty in your startup form,

remember to pass a reference to the main form when you show the startup form ... startupForm.showDialog(this);