Open Radar

 
(This radar was closed as dupe of radar://14761553) 

Summary:

With a dual monitor setup, on the new Mac OS 10.9 Mavericks (DP 5 13A538g), when you drag a Safari 7.0 (9537.54.1) Tab from the Left monitor's screen to the Right screen it vanishes never to be seen again. 

You can only close it using the Menu Bar to select it again.

Any normal user who expects this to work will be in for a surprise when they are unable to find and operate that window anymore.

Steps to Reproduce:

1. Open Safari 7
2. Open Two (or more) website Tabs in ONE Safari Window on the LEFT most monitor
3. Drag one tab out from the Tab Bar into the RIGHT monitor's screen

Expected Results:

The tab will open itself in a new Safari Window in the other monitor's screen

Actual Results:

The website tab's new window is not visible. 

It exists as it's listed under Window in the Menu Bar, which you can then use to select and close it. 

Also if you Merge All Windows with the invisible Window selected, then all the Windows will vanish along with it.

Regression:

Works fine going from the Right Monitor to the Left Monitor, but not from Left to Right.

Didn't happen this way in Safari 6 or Mac OS 10.8. 

Notes:

I've attached my Configuration information as well as a video demonstrating this happening on my Mac Pro. Plus a screen shot of the Display Control Panel's "Arrangement" screen.

Left monitor is 2560x1440 (Apple LED Cinema Display)
Right monitor is 1920x1200 (Apple 24" Cinema Display)

UPDATE #1

Actually talking with my coworker who has a similar setup, and got two more points of data: 

1) It's not Left to Right, it's Primary to Secondary Screen. Primary meaning the one in Arrangement that has the Title Bar and where the Dock exists. 

2) If the Secondary screen already has a Safari Window of any kind, you can successfully drag a Window to that Window or Screen just fine. The bug only happens when that screen has no existing Safari window in it at all. 

UPDATE #2

Also forgot to note, the coworker than can reproduce this is also using a Mac Pro. 

None of us currently can reproduce this on a MacBook Pro Retina + External Screen setup.

EXAMPLE VIDEO AVAILABLE AT: http://cl.ly/0u3R3F0C1o0S