This is an ebuild derived from the qtcurve-qt4-0.61.4.ebuild in the current portage tree, to update to the latest version of the upstream package, and uncomment a define that provides slightly better, although not perfect, tab rendering in qt4.5. Tested on ~amd64, with kde 4.2.1 Reproducible: Always Steps to Reproduce:
Created attachment 184801 [details] The ebuild.
Created attachment 184802 [details, diff] Patch to uncomment the QTC_STYLE_QTTABAR define
Created attachment 184805 [details] Renamed and tested version of the current gtk-engines-qtcurve to bump version.
QtCurve packages have been updated to 0.62.2 I suggest you discuss your patch with the upstream developer.