- create-simple-window now uses a border-width of 0.

- fixed a bug in query-tree.

- added auxiliary functions for query-tree: window-root, window-parent
  and window-children.

- added auxiliary functions for map-state: window-mapped?,
  window-viewable? and window-unviewable?

scheme/xlib/window.scm

@@ -45,7 +45,7 @@
 
 (define (create-simple-window parent width height 
 			      set-window-attribute-alist)
-  (create-window parent 0 0 width height 1
+  (create-window parent 0 0 width height 0
 		 'copy-from-parent 'copy-from-parent 'copy-from-parent
 		 set-window-attribute-alist))
 
@@ -182,6 +182,15 @@
 (define window-override-redirect 
   (make-win-attr-getter (window-attribute override-redirect)))
 
+;; some functions for easier access to the attributes
+
+(define (window-mapped? window)
+  (not (eq? (map-state is-unmapped) (window-map-state window))))
+(define (window-viewable? window)
+  (eq? (map-state is-viewable) (window-map-state window)))
+(define (window-unviewable? window)
+  (eq? (map-state is-unviewable) (window-map-state window)))
+
 ;; The map-window function maps the window and all of its subwindows
 ;; that have had map requests. See XMapWindow.
 
@@ -284,16 +293,35 @@
   (let* ((display (window-display window))
 	 (res (%query-tree (window-Xwindow window)
 			   (display-Xdisplay display))))
-    (list
-     (make-window (vector-ref res 0) display #f)
-     (make-window (vector-ref res 1) display #f)
-     (vector->list (vector-map! (lambda (Xwindow)
-				  (make-window Xwindow display #f))
-				(vector-ref res 2))))))
+    (if res
+	(list
+	 (make-window (vector-ref res 0) display #f)
+	 (make-window (vector-ref res 1) display #f)
+	 (vector->list (vector-map! (lambda (Xwindow)
+				      (make-window Xwindow display #f))
+				    (vector-ref res 2))))
+	res)))
 
 (import-lambda-definition %query-tree (Xwindow Xdisplay)
   "scx_Query_Tree")
 
+(define (window-root window)
+  (let ((t (query-tree window)))
+    (and t (car t))))
+
+(define (window-parent window)
+  (let ((t (query-tree window)))
+    (and t (cadr t))))
+
+(define (window-children window)
+  (let ((t (query-tree window)))
+    (and t (caddr t))))
+
+(define (window-exists? window) ;; maybe this should be done a little
+				;; bit more clever
+  (if (query-tree window)
+      #t #f))
+
 ;; translate-coordinates takes the x and y coordinates relative to the
 ;; source window's origin and returns a list of three elements: the x
 ;; and y coordinates relative to the destination window's origin. If