I want to create a dark theme. But I have failed to see how I would change the background color of the menu row and the colors of the scroll bars even though I have tried looking at the relevant Wiki page.Here is an image indicating what I want to change:
Openbox 3 theme: How to set color for menu background and scroll bars
openbox;theme
The parts of the window you pointed out are rendered by the client, i.e. the application itself. Openbox themes only apply to the window decoration. In order to change the look of your applications you will have to set a GTK theme with a tool like LXAppearance.