...the dmg opened a folder with the pkg icon and an Uninstall icon (among other things that I don't care about). I clicked the pkg and installed Onyx, but I do not see the Unistall icon anywhere on my hard drive.
No doubt the Uninstaller still resides on the .dmg; the fact that it was provided independent of the .pkg implies that it wouldn't be part of an install.
This illustrates why it can be good practice not to routinely discard .dmgs once the application has been installed. (On the downside, of course, a collection of .dmgs can eat up a lot of disk space; my "installers" folder consists of 33 items taking up 3.3 GB.)
