Marcus,
You are not missing anything. If the entire contents of the textbox is selected then where does the arrow key being its movement from? That question in rhertorical, yous ee there is no reference for where the arrow key should start its movement because the inertion point is not at any specific point within the contents. So, the suer either, presses home to move the insertion point ot eh beginnign of the control, or uses the mouse to position the insertion poitn or presses End to move the insertion point to the end on teh contents, or ...