When you click summon retainer > tab with the following option will appear :
Summon your retainer ?
Yes / No
Then again, next tab pops up
with list where you can select your retainer - but also - you can close this tab as well.
And this one is enough. Why to ask if yes / no ? When you can close 2nd tab with retainer list as well...
Its just minor thing.
But this will fasten up a retainers call a bit.