One form accesses controls on a different form - good practice?

[trebor]

I'm learning dotNet, although I first learned programming back in the
days when structured programming was all the rage. In both my books and
courses, I've seen something like this:

Public Class FormA
Inherits System.Windows.Forms.Form

Private Sub Button_Click(ByVal etc., etc.) Handles btnCalculate.Click
FormB.Textbox.Text = "some updated value"
End Sub

Is this good programming practice? Somehow, it just feels wrong to
access a form's controls FROM A DIFFERENT form.

Isn't this no different from A accessing B's local variables? I know
compilers will let you to do it, but I learned that was not good
programming practice because (among other things) a ripple effect could
introduce subtle and difficult bugs.

And if this IS good programming practice, what's the rationale behind
it? What changed over the past 15 years?

[Cor]

Trebor,
I am from before the time of structured programming but a Dijkstra follower
(One of the first inventors of structured programming)

One of the main reasons for structured programming was to keep your program
readable.
(Small parts that could be handled. For that OO programming has no
difference in my opinion).

Public Class FormA
Inherits System.Windows.Forms.Form

Private Sub Button_Click(ByVal etc., etc.) Handles btnCalculate.Click
FormB.Textbox.Text = "some updated value"
End Sub

We often say in this newsgroup that one of the advantage's of VB.net is,
that it has the possibility to do it in your own way.
But I don't think this is good practise I never saw it in that way been
described by someone.
(Sometimes people ask how to do it in this way, but they never get that
answer).

Some thoughts

Cor