Texture Pack list doesn't update the file/pack list without restarting the game

launch MC, Open settings for texture packs, click open folder, add valid texture pack files, exit settings menu, re-open settings menu, List does not update like it did previously

Not sure if affects it, but I have some existing texture pack(s) loaded on launch

(Bug tracker search for 'texture pack' did not reveal a similar issue, i can only assume this has not been reported yet.)