There are a few examples of pairs of words ending with -ee/-er like employee and employer or advisee and adviser. What I was curious about is if there was any rule that would describe the relationship of the objects in a pair like this and situations when it's appropriate to create a counterpart for a given word.
I'll give you an example. It's relatively common in the computer programming world to see the word dragee, which describes an object that is being dragged with a mouse. I understand that this is a relatively new word and could not be found in any dictionary (I've tried). Is that acceptable to make up words like this one or is it just bad English?