I'm doing an experiment on building GTK+3 packages for Slackware-Current. Why? Because many packages will require GTK+3 in the future. Nowadays packages are still linked to GTK+2, which is good because we can save time to work on migration to GTK+3 without rush.
I have added the SlackBuild to my SlackHacks repository. It's based on Slackware's SlackBuild script which i updated and modified in order to work with GTK+3. It requires some upgraded packages which you can find in gimp directory because it was part of my previous hack: UnOfficial Gimp for Slackware-Current.
Even though it compiles nicely, there's still some notes on this package. First, it doesn't come with libgtk-x11, which is required by many applications that were linked with GTK+2, such as Mozilla Firefox, GIMP, Acrobat Reader, etc. The impact will be a broken application. I seached through several other Linux distribution and they ended with same results.
Then, i just realized that made a silly move. I used upgradepkg instead of installpkg. GTK+3 is not meant to replace GTK+2, but to work alongside. Bear this in mind: use installpkg instead of upgradepkg to install this package.
As usual, let me know if there's something wrong with the SlackBuild or if you have some improvements for this package.