[x11] events don't work in testnative

[madebr]

For example, the SDL_EVENT_QUIT event is never triggered (checked with a debugger). This is the complete stdout after clicking on the x:

INFO: Creating native window for x11 driver
X Error of failed request:  BadWindow (invalid Window parameter)
  Major opcode of failed request:  146 ()
  Minor opcode of failed request:  1
  Resource id in failed request:  0x1200001
  Serial number of failed request:  4303
  Current serial number in output stream:  4304

[slouken]

Yeah, foreign windows aren't managed by SDL in any way. This is a common request though, so I'll put it on the SDL 3.0 milestone.

[slouken]

So we've enabled mouse and keyboard events. The close button still doesn't work though.

@icculus, even if I register the WM protocols, we still don't get ClientMessage events for the window. Can you take a look?

[slouken]

We are scoping work for the SDL 3.2.0 release, so please let us know if this is a showstopper for you.