Noticed the new Minecraft launcher (MinecraftDev), unlike the old launcher, opens a separate app when you click “Play”. This is non-standard and undesirable behavior for the Mac OS X desktop; for example:

• Opening the Minecraft launcher while Minecraft is already running will not bring Minecraft to the front as it should (but open a separate copy instead).
• The “Keep in Dock” function of the Dock will either result in two icons in the dock (if the launcher is kept) or a non-functional icon (if Minecraft is kept).

Both of these standard Mac OS X app behaviors worked correctly with the old launcher.