Index: library/ttk/notebook.tcl
==================================================================
--- library/ttk/notebook.tcl
+++ library/ttk/notebook.tcl
@@ -14,10 +14,12 @@
 catch {
 bind TNotebook <Control-ISO_Left_Tab>	{ ttk::notebook::CycleTab %W -1; break }
 }
 bind TNotebook <Destroy>		{ ttk::notebook::Cleanup %W }
 
+ttk::bindMouseWheel TNotebook		[list ttk::notebook::CycleTab %W]
+
 # ActivateTab $nb $tab --
 #	Select the specified tab and set focus.
 #
 #  Desired behavior:
 #	+ take focus when reselecting the currently-selected tab;
@@ -54,16 +56,20 @@
 }
 
 # CycleTab --
 #	Select the next/previous tab in the list.
 #
-proc ttk::notebook::CycleTab {w dir} {
+proc ttk::notebook::CycleTab {w dir {factor 1.0}} {
     if {[$w index end] != 0} {
 	set current [$w index current]
-	set select [expr {($current + $dir) % [$w index end]}]
-	while {[$w tab $select -state] != "normal" && ($select != $current)} {
-	    set select [expr {($select + $dir) % [$w index end]}]
+	set d [expr {$dir/$factor}]
+	set d [expr {int($d > 0 ? ceil($d) : floor($d))}]
+	set tabCount [$w index end]
+	set select [expr {($current + $d) % $tabCount}]
+	set step [expr {$dir > 0 ? 1 : -1}]
+	while {[$w tab $select -state] ne "normal" && ($select != $current)} {
+	    set select [expr {($select + $step) % $tabCount}]
 	}
 	if {$select != $current} {
 	    ActivateTab $w $select
 	}
     }