Looks like nothing in the tree depends on the support for old glade slot, I would then disable it to let us kill one of the remaining consumers of that slot Thanks
+*gtksourceview-2.10.5-r3 (06 Jun 2015) + + 06 Jun 2015; Pacho Ramos <pacho@gentoo.org> +gtksourceview-2.10.5-r3.ebuild: + Drop obsolete glade support (#551290) +
Pretty sure these were behind a USE flag and optional usually only because we don't have a glade-common split out of dev-util/glade that would install the pkgconfig file or something; so that libraries like gtksourceview can query it for the location where to install the glade support files. And this is nothing that something in the tree would use, but something that a developer would use within glade - glade the UI design tool, not libglade - to place gtksourceview widgets into the UI design, in this case. But given as this is old gtksourceview that no-one should be really putting in their UI designs at this point, I of course still agree with the dropping; just wanted to clarify
