xorg 1.15 introduces this extension which has a magical event to notify when a pixmap's size changes, which means that the size never needs to be manually fetched
df0173d feature: support XPRESENT extension to reduce compositing overhead
src/bin/e_comp_object.c | 9 ++++++++-
src/bin/e_comp_object.h | 1 +
src/bin/e_comp_x.c | 28 ++++++++++++++++++++++++++--
src/bin/e_comp_x.h | 1 +
src/bin/e_pixmap.c | 12 +++++++++++-
5 files changed, 47 insertions(+), 4 deletions(-)
Upstream: git.enlightenment.org