This may be my own ignorance, but the only nation I know of in Africa that was dominated and controlled by Whites (Post-Colonialism) was South Africa, of course in spite of their actual numbers in relation to the non-whites in the nation.
The challenge here is to have more African nations and societies dominated and controlled by Whites, obviously keeping in mind that those whites will be a minority and I cannot see a way they'd ever be a majority. This would also be post-decolonization since obviously so long as colonies are run by Europe, whites already dominate and run the society.