Open Radar

 
Summary:

Currently, the Dock automatically switches to another display if you drag the mouse downward at the bottom of the display.

If you have windows at the bottom of that display, moving your mouse to those windows can trigger the Dock switch. As per Fitts’ Law, that bottom edge of the display is a huge target for this behavior.

To add insult to injury, the Dock covers the window content after it has moved.
 
Steps to Reproduce:

1) Move some windows to the bottom edge of an external display
2) Move the mouse to select those windows

As an example, I have two screens with 2560x1440 points (the left is a Retina display on an iMac, the right is a Thunderbolt display). This is what they screens and windows look like:

http://files.iconfactory.net/craig/bugs/DockHell.png

Expected Results:

The Dock should not move accidentally during my work day. Nor should it cover the content of windows after moving.

Actual Results:

At least 20 times per day, I have to move the Dock from the right screen back to the left screen.

Regression:

This became an issue when displays could have separate Spaces. Turning this useful feature off in order to fix the Dock movement is not acceptable.

Notes:

I can understand why the current functionality exists (it’s much easier to explain to and use by the average user.) Power users are more likely to be annoyed by this. A “defaults write com.apple.Dock” command would be a totally acceptable way to implement this enhancement request.

——

There are also many users who don't understand what triggers this functionality, nor how to change it back:

https://twitter.com/robchahin/status/578273523652640768
https://twitter.com/waynedixon/status/578271495014641664

Including myself. Luckily, one of my followers on Twitter explained the magic movement that got my Dock back to where I wanted it.