How To Set up And Use AOE

AOE needs a bit of setup but it's worth the effort.

GCP handles mouse broadcasting and clicking, but there are 2 issues which can throw the targeting off for AOE spells:

The windows may be different aspect ratio (they can be different sizes, but the ratio of width to height must be the same)
The characters may be looking in different directions.

The first problem can be solved by making sure that your AOE casters have the same window aspect ratio.
The 2nd issue requires some preparation, and a procedure to use.

The setup steps are:

Set the aspect ratio properly - divide width by height - make sure that this number is within about 10% for each.
Stand your AOE on top of each other, looking towards a distinctive target.
Make sure the views of each AOE caster look as similar as possible (move up/down, left/right and zoom to adjust)
In the chat window of each AOE caster type "/script SaveView(5)". - You can use any number 1-5 - just make sure you are consistent.

Remember we are talking about AOE, so absolute accuracy is not required - just do the best you can.

Now to cast the AOE, use a GCP command such as:

<<AOECaster1,AOECaster2,AOECaster3>>
macro /script SetView(5)
MouseBroadcast 1
cast MyAOESpell

NOTE: To enter this command:

You will need to be in "full mode" - if not click mode and select "full"
Click views/advanced
Click add - give the command a name when asked.
Enter the command (based on the above - but change the names to your characters, and the spell to the spell you want to cast) in the edit box which pops up.
Hit save
Click views / keys
Find a spare (grey) key and click it.
Select the command you created (listed under the name you chose in step 3) - this will bind the command to the key

This will:

Change the view on all characters to be the same.
Put GCP in mouse broadcasting mode
Cast the AOE spell (actually will start it, the AOE will not go off until you click)

To use:

Make sure the AOE casters are stood on top of each other and facing the same way. (I just have them follow in a straight line, then use SHIFT-S to break the follow - a spread macro will be counterproductive here)
Move the mouse cursor over the window of one of the AOE casters.
Press the key to activate the above command (this will allign the views, start mousebroadcasting, and initiate the cast)
Move the green targeting circle to the place you want to drop the AOE and click.
Press the escape key (to stop the mouse broadcasting)

This sounds complex but with practice, it takes less than a second.