Display problem with laptops: Mirroring vs Extended Desktop
I was having problems with my Dell Latitude D600 laptop. I had used it in extended-desktop mode for a while, with an external monitor connected. Today, I wanted to use it for a presentation, with the projector mirroring what was on my laptop screen. It failed to work… No matter how many times I pressed the Fn-F8 (CRT/LCD) key, the projector would just become an extended portion of the desktop (not a mirror). PowerPoint presentation mode doesn't quite work right on an extended desktop, so I was reduced to leaving PP in "edit" mode on the projector.
How to fix? This pdf (by Robert Ralston of UC Davis) has the path to the answer, under the heading "PC Laptops With ATI graphics".
It didn't work exactly as the pdf states, possibly because I have a slightly older laptop. (Or, maybe, because my projector works differently than his.) His instructions were to start with the projector on, as your second desktop. Use the Display Properties window and uncheck the "Extend Windows Desktop" for the projector (second monitor). Then, on the first monitor, click "Advanced", then "ATI Displays". The second monitor should have a red tab next to it.
Mine did not. It appears as though, when deactivated (when the "extend desktop" was unchecked), the projector detached from windows.
The solution was to start over. Start with the projector on as the second desktop, again. Click "Advanced" on either of the monitors, and go to "ATI Displays". Under the "monitor" quadrant, click the box to make it "Display 1". (Notice that the "panel", i.e. your laptop screen, becomes "Display 2".) Press "Ok". Now, you can pretty much follow the directions above. Go to monitor 2 (in the Display Properties) window and uncheck the "Extend Windows Desktop". This will turn your laptop screen blank. Then, click on monitor 1, Advanced, and ATI Displays. Click the red tab next to "panel". If you hit "Apply", then your laptop screen should re-ignite, and have the same contents as the projector. Success! It will work better if you click the button in the panel quadrant with the concentric circles, so that the laptop panel will be the "primary" monitor if you disconnect.