[marler8997]

Fixes #66. Supersedes #65.

Source.readSynchronousReplyOrEvent(sequence) returns a tagged union: either the reply or an event that arrived before it. Callers that can receive events read in a loop and handle the event as a case of the result, then read the rest of the reply with the new readReplyFull/readReplyHeader:

const reply = while (true) switch (try source.readSynchronousReplyOrEvent(sink.sequence)) {
    .reply => |reply| break reply,
    .event => |kind| switch (kind) {
        .ConfigureNotify => { ... },
        else => try source.rejectEvent(kind),
    },
};
const extents, _ = try source.readReplyFull(reply, .QueryTextExtents);

Source.rejectEvent keeps the previous behavior for unexpected events (skip MappingNotify, log and fail on anything else). The existing helpers (readSynchronousReply1/Full/Header, draft.synchronousQueryExtension, synchronousGetKeyboardMapping, keymap.Full.initSynchronous) keep their signatures and use it, so this is an additive API change and examples that can't receive events are unchanged.

Moba/X sends a ConfigureNotify as soon as a window is created, which crashed the examples that select StructureNotify and then do synchronous requests:

• present and draw track the window size from it while waiting for their QueryTextExtents reply
• testexample logs it (like its event loop) through a small local readReply helper used by all its synchronous requests
• dbe queries the DOUBLE-BUFFER extension before creating the window, since it doesn't need the window

Verification

• zig build install install-xauth test-non-interactive passes; x86_64 windows compiles.
• Through a proxy in front of Xvfb that injects a 600x400 ConfigureNotify after any CreateWindow selecting StructureNotify (mimicking Moba/X): dbe, present, draw, testexample and text all keep running (before this change the first four failed with expected Reply but got ConfigureNotify); a temporary log showed present and draw picking up the 600x400 size. All other examples run normally.
• ReleaseSmall stripped size: hello 163240 → 163400, dbe 175424 → 175496, present 180968 → 181488, testexample 188968 → 189264 bytes.

https://ampcode.com/threads/T-01a14b88-aff8-717e-bb9f-364137832240