How to lock & unlock the Richtextbox control in VB.NET?

Thr is only way to lock %26amp; unlock the richtextbox by property window. but i hav to lock %26amp; unlock it during runtime.How to lock %26amp; unlock the Richtextbox control in VB.NET?
These are the properties for TextBox





Enabled: Default value is True. To disable, set the property to False.


Multiline: Setting this property to True makes the TextBox multiline which allows to accept multiple lines of text. Default value is False.


PasswordChar: Used to set the password character. The text displayed in the TextBox will be the character set by the user. Say, if you enter *, the text that is entered in the TextBox is displayed as *.


ReadOnly: Makes this TextBox readonly. It doesn't allow to enter any text.


Visible: Default value is True. To hide it set the property to False.

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