Hm... first of if you choose qtcurve, then you don't need gtk-kde4. Choose in systemsettings qtcurve theme, hit apply. With any of the gtk frontend for choosing themes (I recommend lxappearance), also choose the QtCurve and logout/login. Now go to the systemsettings and tweak it as you like (set the color, icons, fonts and the rest) and do the logout/login again. Everything should be in place now.
I find that sometimes I need to, in lxappearance, set besides theme, same icons like in the KDE control panel, just to make sure everything is correct.
Also, if you want to really really want to nitpick, open file manager, navigate to /usr/lib/qt4/bin , start qtconfig and select gui style qtcurve. Now literally every qt, Kde, gnome and gtk app should appear the same.