diff --git a/content/treestyletab/bookmarksOverlayEditable.js b/content/treestyletab/bookmarksOverlayEditable.js
index caf3cca6..36f66418 100644
--- a/content/treestyletab/bookmarksOverlayEditable.js
+++ b/content/treestyletab/bookmarksOverlayEditable.js
@@ -171,13 +171,11 @@ var TreeStyleTabBookmarksServiceEditable = {
 			this.menulist.value = (selected || this.blankItem).getAttribute('value');
 		}).bind(this))
 	},
-	_createSiblingsFragment : function TSTBMEditable__createSiblingsFragment(aCurrentItem, aCallback)
+	_doProgressively : function TSTBMEditable__doProgressively(aParams)
 	{
-		var itemsIterator = this._getSiblingItemsIterator(aCurrentItem);
-		var items = [];
-
-		if (this._createSiblingsFragmentTimer)
-			window.clearTimeout(this._createSiblingsFragmentTimer);
+		var name = aParams.name;
+		if (this._doProgressivelyTimers[name])
+			window.clearTimeout(this._doProgressivelyTimers[name]);
 
 		var interval = 100;
 		var step = 10;
@@ -185,24 +183,39 @@ var TreeStyleTabBookmarksServiceEditable = {
 			try {
 				for (let i = 0; i < step; i++)
 				{
-					items.push(itemsIterator.next());
+					aParams.onProgress();
 				}
-				this._createSiblingsFragmentTimer = window.setTimeout(progressiveIteration, interval);
+				this._doProgressivelyTimers[name] = window.setTimeout(progressiveIteration, interval);
 			}
 			catch(e if e instanceof StopIteration) {
+				aParams.onComplete();
+			}
+			catch(e) {
+				Components.utils.reportError(e);
+			}
+			finally {
+				this._doProgressivelyTimers[name] = null;
+			}
+		}).bind(this);
+		this._doProgressivelyTimers[name] = window.setTimeout(progressiveIteration, interval);
+	},
+	_doProgressivelyTimers : {},
+	_createSiblingsFragment : function TSTBMEditable__createSiblingsFragment(aCurrentItem, aCallback)
+	{
+		var itemsIterator = this._getSiblingItemsIterator(aCurrentItem);
+		var items = [];
+		this._doProgressively({
+			name : '_createSiblingsFragment',
+			onProgress : function() {
+				items.push(itemsIterator.next());
+			},
+			onComplete : (function() {
 				this._createSiblingsFragmentInternal(aCurrentItem, items, function(aSiblingsFragment) {
 					aCallback(aSiblingsFragment);
 				});
-			}
-			catch(e) {
-			}
-			finally {
-				this._createSiblingsFragmentTimer = null;
-			}
-		}).bind(this);
-		this._createSiblingsFragmentTimer = window.setTimeout(progressiveIteration, interval);
+			}).bind(this)
+		});
 	},
-	_createSiblingsFragmentTimer : null,
 	_createSiblingsFragmentInternal : function TSTBMEditable_createSiblingsFragmentInternal(aCurrentItem, aItems, aCallback)
 	{
 		var treeStructure = this.getTreeStructureFromItems(aItems);
@@ -217,25 +230,17 @@ var TreeStyleTabBookmarksServiceEditable = {
 
 		var fragment = document.createDocumentFragment();
 
-		if (this._createSiblingsFragmentInternalTimer)
-			window.clearTimeout(this._createSiblingsFragmentInternalTimer);
-
-		var interval = 100;
-		var step = 10;
-		var current = 0;
-		var progressiveIteration = (function() {
-			let id;
-			for (let i = 0; i < step; i++)
-			{
-				id = aItems[current++];
-				if (!id)
-					break;
+		var itemsIterator = Iterator(aItems);
+		this._doProgressively({
+			name : '_createSiblingsFragment',
+			onProgress : (function() {
+				let [index, id] = itemsIterator.next();
 
 				let label = PlacesUtils.bookmarks.getItemTitle(id);
 				let menuitem = document.createElement('menuitem');
 				menuitem.setAttribute('value', id);
 
-				let parent = i;
+				let parent = index;
 				let nest = 0;
 				let disabled = false;
 				while ((parent = treeStructure[parent]) != -1)
@@ -257,17 +262,12 @@ var TreeStyleTabBookmarksServiceEditable = {
 				menuitem.setAttribute('label', label);
 
 				fragment.appendChild(menuitem);
+			}).bind(this),
+			onComplete : function() {
+				aCallback(fragment);
 			}
-			if (id) {
-				this._createSiblingsFragmentInternalTimer = window.setTimeout(progressiveIteration, interval);
-				return;
-			}
-			this._createSiblingsFragmentInternalTimer = null;
-			aCallback(fragment);
-		}).bind(this);
-		this._createSiblingsFragmentInternalTimer = window.setTimeout(progressiveIteration, interval);
+		});
 	},
-	_createSiblingsFragmentInternalTimer : null,
 	_getItemsInFolderIterator : function TSTBMEditable_getItemsInFolderIterator(aId)
 	{
 		var count = 0;
@@ -300,24 +300,15 @@ var TreeStyleTabBookmarksServiceEditable = {
 
 		var itemsIterator = this._getSiblingItemsIterator(aId);
 		var items = [];
-
-		var interval = 100;
-		var step = 10;
-		var progressiveIteration = (function() {
-			try {
-				for (let i = 0; i < step; i++)
-				{
-					items.push(itemsIterator.next());
-				}
-				window.setTimeout(progressiveIteration, interval);
-			}
-			catch(e if e instanceof StopIteration) {
+		this._doProgressively({
+			name : '_createSiblingsFragment',
+			onProgress : function() {
+				items.push(itemsIterator.next());
+			},
+			onComplete : (function() {
 				this._saveParentForInternal(aId, newParentId, items);
-			}
-			catch(e) {
-			}
-		}).bind(this);
-		window.setTimeout(progressiveIteration, interval);
+			}).bind(this)
+		});
 	},
 	_saveParentForInternal : function TSTBMEditable_saveParentForInternal(aId, aNewParentId, aItems)
 	{