How do you hand in quests?

In keyclone I had a interract with target key and slaves had click-to-move enabled, and I used that to hand in quests along with Jamba.

Is there any smarter thing in ISBoxer I should use?

nop its same. as i dont use click to move, il just get close to npc and hit IWT key (what is broadcasted to all) and when all toons have the questbox opened il pick the right quest and il give it in.

I use the broadcasting myself. If the reward is something that I will choose differently for each class, once I get the quest rewards screen up, I turn off broadcasting and switch to individual toons as needed.

You can use mouse broadcasting (repeater) for game ui elements.
Like the quest box.
They'll be in the same position in each window.

But game elements, such as NPC's won't be a perfect match because of camera angle, zoom, following behind etc.
You're best off to target the npc, assist with slaves, interact with target.
Same deal as Keyclone.

I have a keymap, which disables click to move on the main.
When you switch to a character.
And enables click to move on the others.
So IWT + CTM, works for the slaves always, but you don't have movement of the main from clicking.

I just switch toons. There's a better way to do it; i'm just too lazy to sit down and try to figure it out.

You want "CTM" click to move, enabled for the slave toons.
And "IWT" interact with target, keybound on all toons.

Target the npc with the active toon.
Have the slaves assist the active toon.
Hit your IWT keybind.

Then Jamba will have the slaves mimic most of the choices of the main.