My problems were twofold.
First, after updating deps, getting missing deps and running updates I somehow ended up with two versions fltk-1.10 & fltk-1.1.10 didn't notice this at first so meanwhile ran MD5 checking, e2fsck on the volume, even restored the stable release version 4.6.2, Xprogs, wbar + deps, and created a new onboot lst, none were successful of course with every boot failing to install wbar and system apps. Exiting from X allowed the use of poweroff command in order to shutdown meantime.
Apparently we had acquired two versions of fltk. How this occurred is a mystery to me, but removing the earlier version seemed to resolve the issue (at least with 4.7rc4).
It didn't help failing for some reason to change owner/permissions on core 4.6.2, core files, Xprogs, wbar + deps from TinyCore-current.iso used during troubleshooting the missing wbar. Then attempting (unsuccessfully) to overwrite these files when returning to the desired 4.7rc4 versions later on. Simply deleting these 4.6.2 versions of the core files, Xprogs, wbar + deps, then replacing with new RC versions fixed this issue. I hate it when I'm not root, always leads to trouble.