I have a 3rd generation emac running 10.4.11 with 1gb of ram, and a 12" G4 ibook, 10.5.8, both linked by vga adapter to a 19" Dell monitor and this workround works like a charm on both.
There is one massive caveat for all emac users - this script will give you the new facility in Display preferences to have a 90% rotation of your second monitor, if your monitor supports that function.
DON'T CHOOSE IT!!! eMacs don't support rotation. Period.
Having scoured the forums for bad press prior to installing this, the one big area of concern is actually choosing this rotation function on setup, which in 99% of cases has led to total screen weirdness and lack of functionality.You will then only be able to reset your displays back to normal by finding the two apple windowserver plist files, deleting them, and then restarting.
That said, if you can stop yourself ticking the 'rotate' box on startup, you will be rewarded with one of the best pieces of production software available for the Mac.
My displays are sorted.......now, about the fan on my emac that never, ever, turns off....

THIS IS A MUST HAVE!! I just got a 19 inch Samsung SyncMaster 920NW for Christmas and now I can FINALLY use it! I have an iBook G4, and when I plugged the Samsung into it, the screen proportions gave me a headache. Reading the manual made me depressed because Apple said that the maximum screen resolution is 1024 X 768. This download is like saying the hell with that!

1680x1050 isn't supported on the PBG4 as such.

http://developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-G4/PowerBook_G4Apr02/3Input-Output/index.html?http://developer.apple.com/documentation/Hardware/Developer_Notes/Macintosh_CPUs-G4/PowerBook_G4Apr02/3Input-Output/Digital_Dis_Resolutions.html

As the PBG4 supports Dual Displays SSD is the wrong application for you. You should try SwitchResX instead.

Screen Spanning Doctor is a "must have" application for all Ibook owners.

But, there is another problem for all of us: Did you notice that when you have opened an application in a second-extended screen, then shut down your Mac, and restart it with 1 screen, the application remembers where it was opened (i.e. 2nd screen), and it's impossible to select it!!!???

If you do "exposé", you will see that the application is indeed opened, but you won't be able to place it back on the main screen!! A BIG APPLE OS X Bug!

I called Apple and they don't know the solution. "Detecting Displays" won't work. Relaunching Finder doesn't work either.

It's pretty upsetting, because it means that every time you leave home, you have to move back all applications on the main screen before shutting down the Mac (PowerBook).

I guess someone could write a little app that would automatically re-settle the coordinates of applications' screen to "centered window 1".

The contrary is true for Quicktime, which would systematically open a video window on top-left corner of main screen #1, not letting users decide where a QT window should open by default (when working with IMovie, FCE or DVDStudio Pro, it's upsetting to have this QT Window not "positionable" where you want.

If someone, or Screen Spanning Doctor's author, could fix these 2 Apple bugs, it would be a great service for the Apple community.

i agree....this is the greatest download i have got to update the mac.....i can have a movie or work on one screen and be doing totally different on the other....thank you thankyou thankyou...i've needed this for a while now

I've got a computer
Machine Model: PowerBook G4b (titanium)
CPU Type: PowerPC G4 (2.1)
CPU Speed: 550 MHz
I bought a new lcd screen 1650X1050
I want find how can I make my computer compatible with my screen.
TU
Regards