iTunes pause button becomes stop button when importing music
If I have some MP3 files on my computer that have not been imported into iTunes and I import them by selecting them and opening them (thereby opening iTunes, copying the files to the Music folder, and adding it to the library), I noticed that the pause button becomes a stop button when it automatically starts playing a track. If I click the stop button, it stops playing the track, and when I click play again, it is not a pause button.
Why does it change to a stop button in the first place? What is the reasoning for this?
iMac (27-inch Mid 2011), Mac OS X (10.6.8)