I'm despriately trying to figure out a way to display the lightroom secondary display on my monitor to the right of my main display. I'm working in Windows 7 RC which seems to have the same monitor properties as Vista. No matter what I do Lightroom will always choose the display to my left as secondary, I've even tried physically switching my cables for the monitors and it still figures out which display is on the left and displays it there. Is there any way to pick which display is secondary?
The only trick I found is to disable the full screen modus for the second LR window, by right clicking on the small icon at the bottom left, the drag the smaller second preview window to the monitor where you want it to be, and then manually expand it again untill it basically is the same full screen size again. Then afterwards if you close LR and later open it again, it might even remember these settings and open them correctly again.
I found this thread when I was having the same issue and although it didn't help, I did some digging and all of a sudden a light bulb went off, the problem here is actually not with Adobe it is instead a Mac OS problem. I have three monitors my Imac in the center and two HP monitors, one to the left and one to the right. I wanted to be able to be in the develop module while having my grid view on the right monitor. I figured out how to get the "secondary display" up on the third monitor but everytime I went to the other HP Monitor LR would reset and put both windows back on my MAC basically this issue every one is having. After some moments of frustration I realized that I had LR assigned to a paticular desktop, I use three different desktops on my Imac, and now understand this was the problem. If you right click on LR and "assign to all desktops" the secondary display will stay put even when you minimize or use a different app. The secondary display does "go away" but once you go back to LR it will appear again on the secondary display. Hope this helps!
SOLUTION (well, an effortless permanent workaround)
tl;dr: Found a script to easily automate moving and maximizing the secondary window.
After searching the internet for the seventh time, I'm finally happy with the solution I found. It's ten minutes work to install everything, and then you're set forever. (for the solution skip first two points)
Firstly: changing the display order by switching the adapters has no effect. Don't bother. (LR always picks the monitor the most to the top-left or bottom left).
Secondly: The quick but ugly way. In windows display settings, set the location of the screen to the right of your primary monitor and the screen where you want your Secondary LR monitor to the left of it. This should make LR chose the right one. Although, as this probably doesn't reflect your real set-up (as was the case with me) so after ten minutes you'll probably get so fed up that you'll revert the settings. (This is usefull for set-ups with projectors though)
Finally; the SOLUTION:
Download and install AutoHotkey (Just install, there's no settings)
Edit the script on the line with the WinMove instruction (don't worry, it's not rocket science) to set the right coordinates for the screen you want to use. (To find the coordinates, use the "AU3_Spy.exe" program you'll find in the AutoHotkey install folder)
Also note that if your version of Lightroom is in a different language than english, you'll have to change the words "Secondary monitor" in the WinWait line to whatever the title of the secondary monitor window is.
Save the script file wherever you want, and make a shortkey to it in Startup folder so it starts up with Windows. C:\Users\<User>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\
You might have to restart LR or your whole PC for it to start work but now the Secondary Monitor should automatically appear in a maximized window on the screen you defined!
To make it cleaner, you can find and download the app "Borderless Gaming" to make this secondary window appear as fullscreen instead of in a maximized window with title bar.
I hope this helps you out too!
ps: please note that I take no credit for any of the provided apps, scripts or solutions. I just found them, put them together and thought it was worth sharing here...