For whatever reason dev-java/openjfx-8.999 can only be installed if dev-java/openjdk:8 is, and won't accept the prebuilt binary that I do have installed via dev-java/openjdk-bin:8. Checking dev-java/openjfx-11.0.9_p0 shows that it accepts either package in the appropriate slot, so I assume missing the prebuilt binary is a mistake in the 8.999 ebuild.
it's done on purpose as installation procedure for 8 and 11 differs significantly. openjfx:8 copies itself to openjdk:8 directory on installation, but it can be build with either openjdk:8, openjdk-bin-8 or icedtea. dependencies may be still not 100% correct, but it's supposed to run strictly on openjdk:8 and nothing else, I tried to simplify the installation so users don't run into problems like building it with openjdk-bin:8 and running with openjdk:8. there are no plans of adding openjfx support to openjdk-bin:8 or icedtea:8 looks I still need to fix RDEPEND to reflect that I guess to prevent confusion in the future. openjdk:11 copies openjfx:11 zip into it's installation dir on build, hence the difference, but you can still build one with openjdk-bin:11, just not actually use it.
8.999 is gone. Closing
