Because of my locked-resolution, multi-monitor desktop, the only way to get a proper fullscreen Minecraft on my system is to let the Window manager do the fullscreening. (Basically, it sets up a mixture of "maximize", "always on top", and "hide window borders")

For most applications, I can set the Window Manager to do that automatically but, for Minecraft, I have to manually fullscreen it every time I start the game because Minecraft doesn't set any of the identifying properties it should.

My Window manager (Openbox) provides some convenience properties showing the values it matches against, even if they're changed after it's done its check. Here's what the xprop command reports for the Minecraft game window:

_OB_APP_TYPE(UTF8_STRING) = "normal"
_OB_APP_TITLE(UTF8_STRING) = "Unnamed Window"
_OB_APP_CLASS(UTF8_STRING) =
_OB_APP_NAME(UTF8_STRING) =
_OB_APP_ROLE(UTF8_STRING) =

That _OB_APP_TITLE value is especially interesting because, as I understand it, it means that you create the window with the title "Unnamed Window" and then rename after Openbox checks but before I see it.

(Though they're all interesting because they imply that LWJGL has no concept of setting sane defaults for X11 window properties. All the PyGTK apps I've written just use the application's filename to fill those values if I don't set them myself.)

Here's how they're supposed to look in the only valid case for using the term unnamed/untitled:

_OB_APP_TYPE(UTF8_STRING) = "normal"
_OB_APP_TITLE(UTF8_STRING) = "(Untitled)"
_OB_APP_CLASS(UTF8_STRING) = "Leafpad"
_OB_APP_NAME(UTF8_STRING) = "leafpad"
_OB_APP_ROLE(UTF8_STRING) =

Could you please at least set ONE of the class, name, and title properties properly on window creation so I can have my window manager auto-fullscreen Minecraft on a single monitor without shutting off the other one?

As is, it's impossible to match only the game window and trying to force the launcher windows to start fullscreen'd causes things to break.