clean host filter value
fix initial child window position
Merge pull request #599 from koeppea/fix-gtk-win-center

fix initial Gtk child window position
Merge pull request #598 from koeppea/gtk-flush-connfilter

Flush Gtk host filter upon widget creation
Incorrect checksum computation on 64-bit systems #539
don't dereference if array elements are accessed
align union memory
use one anonymous union on stack