Added server-side infrastructure for the thread input structure.
Reimplemented AttachThreadInput() and added GetGUIThreadInfo().

diff --git a/server/window.c b/server/window.c
index e513b87..ad51288 100644
--- a/server/window.c
+++ b/server/window.c
@@ -287,6 +287,9 @@
     }
     else win->next = win->prev = NULL;
 
+    /* if parent belongs to a different thread, attach the two threads */
+    if (parent && parent->thread && parent->thread != current)
+        attach_thread_input( current, parent->thread );
     return win;
 }