xduplic-copier: Use XkbKeycodeToKeysym instead of XKeycodeToKeysym. Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
xduplic-copier: Print error message, rather than segfaulting, if XOpenDisplay fails. Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
xduplic-copier: do not call XmuClientWindow on a null subwindow If you click on the root window, xduplic-copier gets an event with subwindow==0. Current XmuClientWindow crashes if you call it with a null window. Instead, shortcut this: look for subwindow==0 as the way to tell it's the root window.
xduplic-copier: add missing #includes
xduplic-copier: update copyright date and licence to gplv3+
xduplic-copier: as found on chiark