Created attachment 39093 [details]
test case illustrating broken xkb keygrabs

This issue and resulting test case are from Havoc Pennington; I'm just forwarding on.

Running the test case results in an error on recent libX11. First noticed in Ubuntu Lucid, which ships libx11-6 1.3.2. Today, I was able to test top of tree in git and it also results in the same error:

Grabbing keysym 0xff50 keycode 0x6e using xkb
Sending map changes to server
X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  144 (XKEYBOARD)
  Minor opcode of failed request:  9 (XkbSetMap)
  Value in failed request:  0x236e0001
  Serial number of failed request:  19
  Current serial number in output stream:  20

I tested this in an Ubuntu Hardy chroot, which ships 1.1.3, and it ran successfully:

Grabbing keysym 0xff50 keycode 0x6e using xkb
Sending map changes to server
Bound key OK
Xkb event received
XkbMapNotify

I thought that I could try and bisect this, but building the old version of libX11 was a little tricky, and I couldn't get it going.

I was able to verify that it was broken in 1.2, but I couldn't build any of the 1.1.x series. So that should at least help you to narrow it down a little.

Thanks.