I bet you'll have to use an app.
Never really tried to change the color before, but now it seems to be greyed out. W+I / personalization / color. I can change the 'title bars & windows borders, but not taskbar. A google search seemed to suggest this is a 'bug'! Maybe someone knows a workaround or a 'reg' fix.
Thanks in advance

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic