I agree that it is a nice feature to have. Many apps do this, regardless of host OS.
In fact, I just did a test, and on the Mac, it DOES remember the window size and position when I quit the IDE and relaunch it.
I would encourage the OP to get a repeatable case documented and submit it as a bug report in the official spot. Now, if I could just remember where that is, I would post the link.
Anyone?