I will probably be using my Raspberry Pi (running Ubuntu Mate) for remote desktop, but not all of the time. Sometimes I will want to plug it into a monitor. When it's not plugged into a monitor, I'd like it to default to 1024x600, and not the tiny 650-something by 420-something. This way I can use it comfortably via remote desktop. However, and here's the catch: when it's plugged into a monitor (I cannot predict the resolution of the monitor), I want it to use that monitor's resolution. This means I cannot just force hotplug and set the resolution that way, because that will not respect the monitor's resolution.
Edit: I am using x11vnc, which means that the resolution that is shared is dependent on the screen size of the existing X desktop, which is in turn dependent on the monitor (or default resolution).