The Anchor and Dock properties of a form are two separate properties.
Anchor refers to the position a control has relative to the edges of the form. A textbox, for example, that is anchored to the left edge of a form will stay in the same position as the form is resized.
Docking refers to how much space you want the control to take up on the form. If you dock a control to the left of the form, it will stretch itself to the height of the form, but its width will stay the same.
This EXAMPLE can help you understand a bit more.
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