Unfortunately the native Mac OS X dock can’t be used on multiple displays. You can get it setup so that it’s available on both, but what most people are after (myself included) is a seamless dock that spans two external display monitors reliably. I’ve tried all of the suggested approaches mentioned on the Apple stackexchange and Apple support forms, and this is by far the best scenario I’ve chosen to use as part of my everyday work flow.

Mac Dock App on Multiple External Displays

Install uBar 4 Application

This is a third-party app that will replaced the native Mac OS dock. This is mandatory, and unfortunately a license will cost you $30. It is a lifetime license though, and in my opinion it’s a worth the cost for the productivity gains.

uBar Preferences for a Dock Replacement

Out of the box, uBar may not seem like an ideal solution but with the right configuration it’s a 100% replacement for the Mac’s built-in Dock app. The key to configuring it is the Favorites feature. Favorites will allow you to effectively choose the applications that constantly appear in the new bar at the bottom of your screens.

Below are the specific configuration settings you’ll need adjust in order to make this happen, grouped by Preference tab. Here are the steps you’ll need to take in order to make these adjustments:

  1. Install and configure the application, giving access to Mac’s Accessibility tools when prompted
  2. Right click on the uBar at the bottom of the screen and select Preferences
  3. Use the settings provided by the screenshots below

General

uBar Preferences > General

Theme

Areas

uBar Preferences > Areas

Menu

uBar Preferences > Menu

Apps

uBar Preferences > Apps

Date & Time

uBar Preferences > Date & Time

Shortcuts

uBar Preferences > Shortcuts

Advanced

uBar Preferences > Appearance

If you want to know the specific details on these configuration options you can reference the official documentation for uBar on the Brawer Software website.

Adding Favorites to the uBar

Now that you have uBar configured as a solid replacement, the final step will be adding Applications to it as Favorites so that they always appear in the bar. To do this:

  1. Open the Applications folder on your mac
  2. Right click on each application that previously appeared in your Dock and select: Services > Add to uBar Favorites

Once you’d done this for all of the apps you want in your bar, you’re done! The process may seem long and tedious, but trust me that once you finish it you’ll have exactly what you’re after: an awesome replacement for the Mac Dock that spans multiple external display monitors.

Bonus: SizeUp Adjustment for uBar

If you use the SizeUp app to affix applications to portions of your display, you can use the Margins feature to offset your windows so that they don’t overlap the uBar. I do this myself, and it’s one of the main reasons I needed/wanted a Dock that spanned both monitors. If you use the Theme outlined in my configuration settings above then the Screen Edge Margins bottom value can be set to 44 for a perfect alignment with nothing overlapping the uBar.

SizeUp Preferences for uBar Margin Offset

Conclusion

You should now have the end result you’re after: a Dock on your Mac that spans dual displays / two external monitors consistently that serves as a complete replacement for the built-in Mac OS Dock app.

About the Author

Kevin Leary is a freelance web developer in Boston, MA specializing in enterprise WordPress development, conversion optimization and JavaScript development.