--- u_main.tk	2006-08-15 18:09:57.000000000 +0200
+++ u_main.tk	2006-09-04 10:12:10.000000000 +0200
@@ -1137,6 +1137,7 @@
 # bother with modifiers there.
 # We don't handle multiple clicks yet.
 
+    bind $name.c <Configure> { pdtk_canvas_autoscrollbars %W %w %h }
     bind $name.c <Button> {pdtk_canvas_click %W %x %y %b 0}
     bind $name.c <Shift-Button> {pdtk_canvas_click %W %x %y %b 1}
     bind $name.c <Control-Shift-Button> {pdtk_canvas_click %W %x %y %b 3}
@@ -1430,6 +1431,19 @@
 #get the name of the toplevel window for a canvas; this is also
 #the name of the canvas object in Pd.
 
+proc pdtk_canvas_autoscrollbars {name x y} {
+    set size [$name bbox all]
+    set x2 [lindex $size 2]
+    set y2 [lindex $size 3]
+    set rootname [winfo parent $name]
+    if {$x > $x2} {pack forget $rootname.scrollhort}
+    if {$y > $y2} {pack forget $rootname.scrollvert}
+    if {$x < $x2} {pack $rootname.scrollhort -side bottom \
+                        -fill x -before $rootname.c}
+    if {$y < $y2} {pack $rootname.scrollvert -side right \
+                        -fill y -before $rootname.c}
+}
+
 proc canvastosym {name} {
     string range $name 0 [expr [string length $name] - 3]
 }