Packages with the gtk3 use flag

app-i18n / fcitx : Fcitx (Flexible Context-aware Input Tool with eXtension) input method framework

Install input method module for GTK+ 3

app-i18n / ibus : Intelligent Input Bus for Linux / Unix OS

Enable the GTK-3 input method module

app-i18n / scim : Smart Common Input Method (SCIM) is an Input Method (IM) development platform

Enable support for x11-libs/gtk+:3

app-i18n / scim-anthy : Japanese input method Anthy IMEngine for SCIM

Enable support for x11-libs/gtk+:3

app-i18n / scim-sunpinyin : SunPinyin IMEngine for SCIM

Enable support for x11-libs/gtk+:3

dev-games / aseprite : Animated sprite editor & pixel art tool

Enable support for the experimental native GTK File Dialog

dev-libs / libdbusmenu : Library to pass menu structure across DBus

Enable support for GTK+3

dev-python / matplotlib : Pure python plotting library with matlab like syntax

Enable x11-libs/gtk+:3 support

media-gfx / geeqie : A lightweight GTK image viewer forked from GQview

Link against x11-libs/gtk+:3 instead of x11-libs/gtk+:2

media-libs / libcanberra : Portable sound event library

Enables building of gtk+3 helper library, gtk+3 runtime sound effects and the canberra-gtk-play utility. To enable the gtk+3 sound effects add canberra-gtk-module to the colon separated list of modules in the GTK_MODULES environment variable.

media-libs / opencv : A collection of algorithms and sample code for various computer vision problems

Enable x11-libs/gtk+:3 support

net-analyzer / pinger : Cyclic multi ping utility for selected adresses using GTK/ncurses

Install the gtkpinger GUI utility based on x11-libs/gtk+:3

net-misc / spice-gtk : Set of GObject and Gtk objects for connecting to Spice servers and a client GUI

Build the spice client (spicy), requires x11-libs/gtk+:3

x11-misc / grsync : A gtk frontend to rsync

Link against x11-libs/gtk+:3 instead of x11-libs/gtk+:2

x11-themes / arc-theme : A flat theme with transparent elements for GTK 2/3/4 and GNOME Shell

Install GTK+3 theme