Index: ChangeLog
==================================================================
--- ChangeLog
+++ ChangeLog
@@ -1,5 +1,14 @@
+2012-04-22  Donal K. Fellows  <dkf@users.sf.net>
+
+	* generic/tkBind.c (ExpandPercents): [Bug 3520202]: Ensure that the
+	%k, %K and %N substitutions use dummy tokens with <MouseWheel> events
+	and that the %D subsitution is a dummy with <Key>/<KeyRelease>. This
+	was causing significant indigestion (and a read of goodness knows what
+	memory) to Tkinter/Python because of the way they map events between
+	languages.
+
 2012-04-20  Jan Nijtmans  <nijtmans@users.sf.net>
 
 	* generic/tk.tcl: Use vroot size in stead of screen size for
 	clipping window coordinates in ::tk::PlaceWindow.
 	* generic/dialog.tcl: Use ::tk::PlaceWindow in dialog.tcl, in

Index: generic/tkBind.c
==================================================================
--- generic/tkBind.c
+++ generic/tkBind.c
@@ -2381,11 +2381,11 @@
 		TkpPrintWindowId(numStorage, eventPtr->xany.window);
 	    }
 	    string = numStorage;
 	    goto doString;
 	case 'k':
-	    if (flags & KEY) {
+	    if ((flags & KEY) && (eventPtr->type != MouseWheelEvent)) {
 		number = eventPtr->xkey.keycode;
 		goto doNumber;
 	    }
 	    goto doString;
 	case 'm':
@@ -2521,29 +2521,29 @@
 	case 'D':
 	    /*
 	     * This is used only by the MouseWheel event.
 	     */
 
-	    if (flags & KEY) {
+	    if ((flags & KEY) && (eventPtr->type == MouseWheelEvent)) {
 		number = eventPtr->xkey.keycode;
 		goto doNumber;
 	    }
 	    goto doString;
 	case 'E':
 	    number = (int) eventPtr->xany.send_event;
 	    goto doNumber;
 	case 'K':
-	    if (flags & KEY) {
+	    if ((flags & KEY) && (eventPtr->type != MouseWheelEvent)) {
 		char *name = TkKeysymToString(keySym);
 
 		if (name != NULL) {
 		    string = name;
 		}
 	    }
 	    goto doString;
 	case 'N':
-	    if (flags & KEY) {
+	    if ((flags & KEY) && (eventPtr->type != MouseWheelEvent)) {
 		number = (int) keySym;
 		goto doNumber;
 	    }
 	    goto doString;
 	case 'P':