diff --git a/content/treestyletab/treestyletabbrowser_autoHide.js b/content/treestyletab/treestyletabbrowser_autoHide.js
index 2d0f7010..5e1bc104 100644
--- a/content/treestyletab/treestyletabbrowser_autoHide.js
+++ b/content/treestyletab/treestyletabbrowser_autoHide.js
@@ -621,7 +621,7 @@ TreeStyleTabBrowserAutoHide.prototype = {
 	{
 		/* PUBLIC API */
 		var event = document.createEvent('Events');
-		event.initEvent('TreeStyleTabAutoHideStateChanging', true, false);
+		event.initEvent(this.kEVENT_TYPE_AUTO_HIDE_STATE_CHANGING, true, false);
 		event.shown = this.expanded;
 		event.state = this.state;
 		this.mOwner.browser.dispatchEvent(event);
@@ -631,7 +631,7 @@ TreeStyleTabBrowserAutoHide.prototype = {
 	{
 		/* PUBLIC API */
 		var event = document.createEvent('Events');
-		event.initEvent('TreeStyleTabAutoHideStateChange', true, false);
+		event.initEvent(this.kEVENT_TYPE_AUTO_HIDE_STATE_CHANGE, true, false);
 		event.shown = this.expanded;
 		event.state = this.state;
 		event.xOffset = this.XOffset;
diff --git a/modules/utils.js b/modules/utils.js
index 7f9ab607..99eebe34 100644
--- a/modules/utils.js
+++ b/modules/utils.js
@@ -119,6 +119,8 @@ var TreeStyleTabUtils = {
 	kEVENT_TYPE_FOCUS_NEXT_TAB               : 'TreeStyleTabFocusNextTab',
 	kEVENT_TYPE_PRINT_PREVIEW_ENTERED        : 'TreeStyleTabPrintPreviewEntered',
 	kEVENT_TYPE_PRINT_PREVIEW_EXITED         : 'TreeStyleTabPrintPreviewExited',
+	kEVENT_TYPE_AUTO_HIDE_STATE_CHANGING     : 'TreeStyleTabAutoHideStateChanging',
+	kEVENT_TYPE_AUTO_HIDE_STATE_CHANGE       : 'TreeStyleTabAutoHideStateChange',
 
 	kTOPIC_INDENT_MODIFIED              : 'TreeStyleTab:indentModified',
 	kTOPIC_COLLAPSE_EXPAND_ALL          : 'TreeStyleTab:collapseExpandAllSubtree',