Unifying mergetool configuration between git and git-gui

Hi,

I was about to add a configuration for yet another mergetool when I realized that git gui's mergetool.tcl pretty much duplicates git's mergetools/* configuration files. Can some one tell me why this is necessary? I would have expected git gui to simply rely on "git mergetool" to launch the mergetool. Or, in case that git gui needs to use a different tool than the one configured as mergetool, that mergetool.tcl somehow uses the configuration from mergetools/*.

Thanks for any insights.