Open Radar

 
Summary:

If the dock is placed on the left side of the screen and then pinned to the start (top left corner) the dock icons will not be in the correct position on the dock when one of the following happens:

- The screen resolution changes
- An external monitor is plugged in, while in clamshell mode
- An external monitor is unplugged, while in clamshell mode, and the macbook is opened

Steps to Reproduce:

1.  Place dock on left side of screen.
2.  Pin dock to start: defaults write com.apple.dock pinning -string start && sudo killall Dock
3.  System Preferences > Displays > Change to Scaled Resolution

Expected Results:

The dock icons should be in their normal places.

Actual Results:

The dock icons are all translated down the screen by a number of "app positions."  I.e., a number of pixels corresponding to the width of a dock position.  The icons extend past the dock boundary.

Notes:

Moving the mouse over the dock resets the display.

This happens on a 2008 MacBook Pro 17" and a 2012 Retina MacBook Pro 15" and has been present since at least OS X 10.6.