[Gerrit Vanoppen]

This is the Finder Preferences pane, but the horizontal white lines also come up when unfolding other icon bars (like System Preferences) by clicking the Toolbar button at the top right.
Can anyone tell me which ThemePark resource would have to be corrected in order to have a plain gray background ?
TIA

[Makki]

by the looks of it it is toolbar background

[.saNNic.]

Isn't that Browser>Toolbar Background?

I'm not quite sure without looking...........

[Gerrit Vanoppen]

Thanks, that was quick.
Found it at : my theme/Elements/Global Elements/Toolbars/Toolbar Background.