Sometimes, on removal SDL_EVDEV_udev_callback() gets called with zero udev_class. This in turn seems to be caused the SDL_udev.c:guess_device_class() failing to find the attributes of the parent device.
Apparently this is normal, attributes are not guaranteed to be in place during removal, depending on timing. This lack of attributes causes guess_device_class() to return zero.
This fix mimics the code in linux/SDL_sysjoystick.c:joystick_udev_callback() which effectively has the same fix already in place.
+ Handle HidePreeditText IBus signal.
+ Use SDL_GetKeyboardFocus instead of SDL_GetFocusWindow.
+ Move the X11 IBus SetFocus calls to the X11_DispatchFocus functions.
+ Simplify the IBus ifdefs when handling X11 KeyEvents.
+ Remove inotify watch when SDL_IBus_Quit is called.
Ashley Whetter
RHEL6 and CentOS6 systems still use an old version of udev (147). It wasn't until udev 148 (Yep. 1 version off!) that the input class system changed from "ID_CLASS" to "ID_INPUT_{JOYSTICK,KEYBOARD,MOUSE,etc}" (http://lwn.net/Articles/364728/). Because SDL2 looks for the ID_INPUT_X field this means that it never detects any input devices on RHEL6 systems.
I've attached a patch which fixes the problem. If no input devices are detected with "ID_INPUT_X" then SDL will fallback to looking for the old style "ID_CLASS" udev field instead.
Because of the "big change" between udev versions I doubt it'll ever get upgraded on RHEL6, but because RHEL7 is on the way I don't know if this patch is worth merging. Hopefully it'll help anyone out that's having this problem though.
Ryan C. Gordon
To keep the directory layout sane, we should probably move this one piece of source to the linux catch-all directory, instead of making it look like this is part of an SDL "input" subsystem.
