I've submitted an issue for this with Adobe but, perhaps because of some communication issues, they have reported that they are unable to reproduce the problem. My question to the community is - can anyone else verify the following - using my steps and explanation?
Environment: iMac 27" with only the single monitor.
Basic Description of Problem:
After invoking the window for a "second monitor" - which pops up on top of my main display screen, I can close the second window and click on items which were hidden under the second window. If, however, I switch to another "Desktop Space" on the Macintosh and switch back, the area where the second monitor window was located becomes a "dead space" where mouse clicks to select something no longer work.
My current workarounds:
1. Open and close the secondary window again - and the area "covered" by the window will start responding (problem is - you need to do this every time - a pain if you set up something like PhotoShop CS6 and Photomatix in different Desktop Spaces to switch to when processing).
2. Move the window as far as you can off the screen - so the area doesn't overlap anywhere you'd want to click. This works as long as Lightroom is running. If you quit, however, the window position coordinates are updated (even if the window is closed) so the entire window is located within a valid monitor area.
Step-by-Step (somewhat abbreviated since this isn't a QA report forum ;)
1. Launch Lightroom and - just to ensure you're really able to see the issue (and working the way I do) - make sure the display is mostly maximized to fill the monitor.
2. Switch to Library (if not there already) and switch to Grid view.
3. Either click on the icon to open the "secondary display" or - go to the menu option Window>Secondary Display>Show to open the window.
4. Just to make this obvious - if it happens - resize this new window (on top of your main display - remember - I have only the one display) - so large it covers many of the image previews displayed in "Grid" mode.
5. Close (Hide) the secondary window display. Either click the close button - or use the Window menu to deselect "Show".
6. At this point - I can click on images which were previously covered by the secondary window - and my mouse clicks select the images, etc.
7. Switch to another desktop. Use "control + right arrow" or something.
8. Switch back to the desktop space where Lightroom is located.
9. Try clicking on an image in the grid view which was previously covered by the secondary window.
Does it respond? In every case - my mouse clicks fail at this point. It's as if the secondary window - while "closed" - is now masking the main display after switching to another desktop and back.