Discrepancy between XCB and X11 MappingNotify

[qqdpv04z at thepsauce.anonaddy.com]

> Have you traced the protocol with xscope or xtrace? That would let you
> see if the events are being delivered from the server and lost inside
> the library somewhere.
Good idea, I tried this with "xtrace" now with all three cases. Using only xcb
got the expected MappingNotify events in the other cases not. However, it looks
like libX11 does a lot more when doing XOpenDisplay():
... auth
000:<:0001: 20: Request(98): QueryExtension name='BIG-REQUESTS'
000:>:0001:32: Reply to QueryExtension: present=true(0x01) major-opcode=133 first-event=0 first-error=0
000:<:0002:  4: BIG-REQUESTS-Request(133,0): Enable
000:>:0002:32: Reply to Enable: maximum-request-length=4194303
000:<:0003: 20: Request(55): CreateGC cid=0x04800000 drawable=0x000003db values={background=0x00ffffff}
000:<:0004: 24: Request(20): GetProperty delete=false(0x00) window=0x000003db property=0x17("RESOURCE_MANAGER") ...
000:>:0004:1072: Reply to GetProperty: type=0x1f("STRING") bytes-after=0x00000000 data=...
000:<:0005: 20: Request(98): QueryExtension name='XKEYBOARD'
000:>:0005:32: Reply to QueryExtension: present=true(0x01) major-opcode=135 first-event=85 first-error=137
000:<:0006:  8: XKEYBOARD-Request(135,0): UseExtension major=1 minor=0
000:>:0006:32: Reply to UseExtension: major=1 minor=0

I guess (looking at src/OpenDis.c within libx11) these additional messages are
caused by XkbUseExtension(...) etc. They are no surprise. But maybe this call
causes no MappingNotify event to be sent?