Since 5.2 SetFocus and ClearFocus now work from the dropdown menu, so you can remove the following code from blizzard.lua

for _, menu in pairs(UnitPopupMenus) do
for index = #menu, 1, -1 do
if
menu[index] == 'SET_FOCUS' or
menu[index] == 'CLEAR_FOCUS'
then
table.remove(menu, index)
end
end
end

Solved with 6b5d243.