I’ve been trying to compile hoodle following the instructions in the readme: https://github.com/wavewave/hoodle Went further than year or two earlier when attempt got mired in cabal-hell This time stack build went through (after a couple of deb packages needing installation) Now I get this error on trying to run GTK+ 2.x symbols detected. Using GTK+ 2.x and GTK+ 3 in the same process is not supported Asking on the hoodle mailing list I was told that one has to build poppler with option -fgtk3 Where/How to give that? Looking at https://github.com/commercialhaskell/stack/issues/191 I tried the following: 1. Delete every file/directory under .stack-work that has the word poppler 2. stack build poppler --flag gtk:gtk3 3. stack build Seems to have built Ok I get the same warning that stack seems to be generally giving — dozens of them — viz ============ No packages found in snapshot which provide a "gtk2hsC2hs" executable, which is a build-tool dependency of "glib" Missing build-tools may be caused by dependencies of the build-tool being overridden by extra-deps. This should be fixed soon - see this issue https://github.com/commercialhaskell/stack/issues/595 ============= But thereafter stack exec hoodle results in the same error. So whats the official way of putting the -fgtk3 flag into stack? Any other suggestions? stack first tried from deb; then redone from stack website $ ghc --version The Glorious Glasgow Haskell Compilation System, version 7.10.3 ubuntu 16.4 (if that matters) Thanks