I use two monitors on my computer for professional reasons at home.

I've noticed that when in fullscreen the mouse is able to leave the game window, and you are able to click outside the game. (In this case, on the non-primary window).

This causes a similar crash to what has been reported by users alt-tabbing. However, in this case this issue can be triggered by something as simple as an accidental mis-click too close to the screens edge. (such as when interacted with the main menu)

The error reported is "Unable to detect DirectX device. The program has shut down. Please restart FINAL FANTASY XIV"

This causes playability issues for a number of reasons:
Forced caution around any of the screen edges adjacent to another monitor.
Forced to use a minimized window instead. (In my case, 1920x1080 which is the native resolution) This would be fine except it has a couple consequences, namely:
  • Without the aid of a 3rd party program to remove borders, running at 1920x1080 causes the game to overlap to the next montior, causing a severe drop in performance due to how primary/secondary monitor relationships are handled by some nvidia cards
  • Due to above, forced to use the next possible resolution of 1680x1050; smaller than I would like, have gaps on left and right.
  • Performance issues due to being windowed. Where as normally I could run most settings set to high or highest with no noticeable drop in framerate; when windowed the frame rate stutters unless everything is set to standard or lower. This would be a severe issue in terms of graphical quality considering the graphics are a main selling point

A possible solution would be to replace the current error handling for a lost Direct3DDevice handle and just recapture the device when focus returns to the game. (This is typically simple to do. The API you are using likely offers one or several built-in helper functions to handle this for you.)

Note that in my case disabling the second monitor is not an option. Typically I have monitoring software for work running in the background and displayed on the secondary monitor, which I need to keep an eye on while on call. (I work in IT support)