For the checkbox issue, I believe that something else on your form is interferring with the behavior here as the default is to check the box as soon as it is clicked.

Try creating a new form with a checkbox on it and you will see that it behaves correctly.
Perhaps some other event like mouseClick is being trapped on the form and handled?

For the TextBox issue:

A standard Windows Forms TextBox control does not support an Overwrite mode by default.
A MaskedTextBox control does have a property called InsertKeyMode which can be set to Insert or Overwrite depending on your needs.

I found an example of how to implement the insert/overwrite toggle within a standard TextBox and I have converted it to COBOL as follows:

       class-id testinsertmode.Form1 is partial
                 inherits type System.Windows.Forms.Form.
       
       working-storage section.
       01 insert-mode   condition-value value true.
       method-id NEW.
       procedure division.
           invoke self::InitializeComponent
           goback.
       end method.

       method-id textBox1_KeyPress final private.
       
       procedure division using by value sender as object e as type System.Windows.Forms.KeyPressEventArgs.
           
           if insert-mode
              exit method
           else
              if textBox1::SelectionStart < textBox1::TextLength and Not type Char::IsControl(e::KeyChar)
                 declare SaveSelectionStart as binary-long = textBox1::SelectionStart
                 declare sb = new type StringBuilder(textBox1::Text)
                 set sb[textBox1::SelectionStart] to e::KeyChar
                 set textBox1::Text to sb::ToString
                 set textBox1::SelectionStart to SaveSelectionStart   1
                 set e::Handled to true
              end-if
           end-if.
           
       end method.

       method-id textBox1_KeyDown final private.
       procedure division using by value sender as object e as type System.Windows.Forms.KeyEventArgs.
           if e::KeyData = type Keys::Insert and insert-mode
              set insert-mode to false
           else
              if e::KeyData = type Keys::Insert and not insert-mode
                 set insert-mode to true
              end-if
           end-if
           
       end method.

       end class.

Thank You, This worked Great. Just what I wanted.

Thank You, This worked Great. Just what I wanted.