well, this might be why the apply button is there! You simply add a quicktext, click apply, test it in an opened conversation window then you can go back to the preferences window and continue editing. I would also like this feature, becuase my solution doesnt always apply, like if you want to continue working on one from an hour ago or so.
I usually use the quick button in the convo. window, and there are other uses to. Say Quick text 43 has a typo - luck you, you get to press the next button 43 times! ....