shiny/driver/gldriver: be less racy wrt size events.

Set the cached value on the receiver side of the channel
communication, not spawned by a goroutine 'soon' after the send.

This CL only affects x11. The same change applies in principle to cocoa
and win32, but I have not (manually) tested it there yet.

Change-Id: Ibe4bad965fe0c059378daef2f535dcae362447a9
Reviewed-by: David Crawshaw <>
4 files changed