Hmm ... It's impossible ;-) This RPM doesn't exist on any FTP server

Provides :
gtkhtml3-devel
gtkhtml3-devel(x86-64)
pkgconfig(gtkhtml-editor-4.0)
pkgconfig(libgtkhtml-4.0)

Requires :

pkgconfig(cairo) => 1.10.0
rpmlib(FileDigests) <= 4.6.0-1
rpmlib(CompressedFileNames) <= 3.0.4-1
pkgconfig(gtk+-3.0) => 3.2.0
pkgconfig(enchant) => 1.1.7
pkgconfig(gsettings-desktop-schemas)
/usr/bin/pkg-config
pkgconfig(iso-codes)
pkgconfig(libgtkhtml-4.0)
gtkhtml3 = 4.8.5-2.el7
rpmlib(PayloadIsXz) <= 5.2-1
libgtkhtml-4.0.so.0()(64bit)
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
libgtkhtml-editor-4.0.so.0()(64bit)

Content of RPM :
/usr/include/libgtkhtml-4.0
/usr/include/libgtkhtml-4.0/editor
/usr/include/libgtkhtml-4.0/editor/gtkhtml-editor-actions.h
/usr/include/libgtkhtml-4.0/editor/gtkhtml-editor-common.h
/usr/include/libgtkhtml-4.0/editor/gtkhtml-editor-widgets.h
/usr/include/libgtkhtml-4.0/editor/gtkhtml-editor.h
/usr/include/libgtkhtml-4.0/editor/gtkhtml-spell-checker.h
/usr/include/libgtkhtml-4.0/editor/gtkhtml-spell-language.h
/usr/include/libgtkhtml-4.0/gtkhtml
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml-embedded.h
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml-enums.h
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml-properties.h
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml-search.h
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml-stream.h
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml-types.h
/usr/include/libgtkhtml-4.0/gtkhtml/gtkhtml.h
/usr/include/libgtkhtml-4.0/gtkhtml/htmlenums.h
/usr/include/libgtkhtml-4.0/gtkhtml/htmltokenizer.h
/usr/include/libgtkhtml-4.0/gtkhtml/htmltypes.h
/usr/lib64/libgtkhtml-4.0.so
/usr/lib64/libgtkhtml-editor-4.0.so
/usr/lib64/pkgconfig/gtkhtml-editor-4.0.pc
/usr/lib64/pkgconfig/libgtkhtml-4.0.pc