For anyone wanting to try it, the arguments for +powertrayexec are : 0 at-will 1, 1 at-will 2, 2 encounter 1, 3 encounter 2, 4 encounter 3, 5 daily 1, 6 daily 2
I am in the habit of using my mouse for executing most powers. Using scroll-up and scroll-down with ground-targeting skills is problematic since the option "Location Targeting Activation On Release" doesn't work with them. The previous command has the additionnal advantage of fixing this problem.
For anyone interested, the arguments for binding mouse butons with the "/bind" command are : "lbutton" for left button, "rbutton" for right button, "mbutton" for middle press, "wheelplus" for scroll-up, "wheelminus" for scroll-down
If anyone knows an easier way of achieving this I'm all ears.
EDIT --- I found a flaw in this.
If a player is standing between you and the target, the hardtargetlock command will lock on the player instead of the target. This causes two problems :
1- if the power is ground targeted it will fire on the player's location
2- if the power can't be used on players it won't fire at all