/POPMENU images.
You can't add images to popmenus. It's just one of many things they don't support. Sorry.

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sadface. how did they manage it with their own ingame menu then? i hope one day they will release this to us. was just getting excited with this.
Simple -- the devs are wizards.
"You don't lose levels. You don't have equipment to wear out, repair, or lose, or that anyone can steal from you. About the only thing lighter than debt they could do is have an NPC walk by, point and laugh before you can go to the hospital or base." -Memphis_Bill
We will honor the past, and fight to the last, it will be a good way to die...
Don't think anyone has found the other menus to see how the images are added. Or even if the other right click menus are coded the same way as the popmenu... I know I looked for a long time, I want to lose the short cut keys on all but the /menu menu.
If you mean the Mastermind Pet Command Window, and the Icons it has, well, that's not a Popmenu. We have no access to that, so we can't modify it.

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You want info on the Help Menu configurer in which you can have images and commands hyperlinked in.
See here.
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I totally forgot about that. >.<

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i'm not certain if anyone is aware of it anymore, but it is found on these links; /popmenu.
http://boards.cityofheroes.com/showthread.php?t=136343 by TheUnnamedOne, and
http://boards.cityofheroes.com/showthread.php?t=127186 by Fleeting Whisper.
both of which were Extremely helpful, explained everything nicely and i have fully functioning popmenu's working with just about all the works. ingame, this is viewed mostly as quickchat, the little bubble on the chat box that people use when they forget the commands for certain emotes. this is Also found in places, such as right clicking a player, enemy and pets, if i'm not mistaken... they look about the same, except for the pets. which is where im interested in.
does anyone know how i can specifically include the IMAGE of the power i want to go off? example, right clicking a pet, you can see the image of Dismiss (an X) and the option Dismiss, which will dismiss the pet. i'm wondering, is there a way i can do that, but say, i want to include the power icon of Destiny's Barrier, for my option to swap from one of my destiny incarnates to Barrier with;
option [barrier image] &Barrier Core "incarnate_equip destiny Barrier_Core_Epiphany"
it'd take me closer in being in touch with my pets. this is what i have built up so far;
http://i56.tinypic.com/abpjtk.jpg
thanks to whoever has the time to research, i have NO idea where to look! Fleeting Whisper had found the file for Quickchat, but i'd be Very intriged by the file for pet commands. thanks!