I'm Green in English,hope someone can read it and catch my meaning... @_@
I think EVERY HEALER in a raid needs a addon to observe other healers' casting bars when they are casting healing spell to the current target in real time, so they can consider if breaking up the healing spell is necessary to avoid over-healing.
I find an addon called DorjeHealingBars, but the author has not updated for a long time, and it can?t work well any more in the TBC.
Hope someone can update it or produce a new one to replace it. Thanks.
Take a look at Visual Heal, I believe it does exactly what you're asking for. While I'm healing someone else, I get a popup health bar that shows how much incoming healing that target has, both from me and from other people, provided they have HealComm-3.0 installed.