diff --git a/content/treestyletab/treestyletab.css b/content/treestyletab/treestyletab.css
index 8774de62..5729f308 100644
--- a/content/treestyletab/treestyletab.css
+++ b/content/treestyletab/treestyletab.css
@@ -120,6 +120,18 @@ tabbrowser[treestyletab-tabbar-autohide-mode="1"][treestyletab-tabbar-autohide="
 	overflow-y: auto !important;
 }
 
+.tabbrowser-tabs[treestyletab-mode="vertical"]
+  .tabbrowser-arrowscrollbox
+  .scrollbox-innerbox {
+	-moz-box-flex: 1 !important;
+	-moz-box-pack: start !important;
+}
+
+.tabbrowser-tabs[treestyletab-mode="vertical"]
+  .tabbrowser-tab {
+	-moz-box-flex: 0 !important;
+}
+
 .tabbrowser-tabs[treestyletab-mode="vertical"] .tabs-alltabs-button, /* -Firefox 3.6 */
 .tabbrowser-tabs[treestyletab-mode="vertical"] .close-button.tabs-closebutton, /* -Firefox 3.6 */
 #TabsToolbar[treestyletab-mode="vertical"] > toolbarbutton,
diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index 99ae9ae8..e3f64fb8 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -3077,23 +3077,6 @@ TreeStyleTabBrowser.prototype = {
  
 	onDblClick : function TSTBrowser_onDblClick(aEvent) 
 	{
-		if (this.isVertical &&
-			/^(?:(?:arrow)?scrollbox|tabs)$/.test(aEvent.originalTarget.localName)) {
-			// re-send dblclick event from the inner-box of the scrollbox,
-			// because Firefox's event listener (to open new tabs) handles
-			// events only from the box.
-			let box = this.mTabBrowser.tabContainer.mTabstrip;
-			if (box && box._scrollbox) box = box._scrollbox;
-			if (box) box = document.getAnonymousNodes(box)[0];
-			if (box && box.localName == 'box') {
-				let event = document.createEvent('MouseEvents');
-				event.initMouseEvent('dblclick', true, true, window, aEvent.detail, aEvent.screenX, aEvent.screenY, aEvent.x, aEvent.y, aEvent.ctrlKey, aEvent.altKey, aEvent.shiftKey, aEvent.metaKey, aEvent.button, null);
-				box.dispatchEvent(event);
-			}
-			aEvent.preventDefault();
-			aEvent.stopPropagation();
-			return;
-		}
 		let tab = this.getTabFromEvent(aEvent);
 		if (tab &&
 			this.hasChildTabs(tab) &&
diff --git a/skin/classic/treestyletab/square/dropshadow.css b/skin/classic/treestyletab/square/dropshadow.css
index ba28b9fc..6e2f43a7 100644
--- a/skin/classic/treestyletab/square/dropshadow.css
+++ b/skin/classic/treestyletab/square/dropshadow.css
@@ -5,25 +5,26 @@
 
 .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabbrowser-tab:not([pinned="true"]) {
-	-moz-box-shadow: -0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15) !important;
-	box-shadow: -0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15) !important;
+	-moz-box-shadow: -0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15);
+	box-shadow: -0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15);
 }
 
 .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"][treestyletab-tab-inverted="true"]
   .tabbrowser-tab:not([pinned="true"]) {
-	-moz-box-shadow: 0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15) !important;
-	box-shadow: 0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15) !important;
+	-moz-box-shadow: 0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15);
+	box-shadow: 0.3em 0.3em 0.2em rgba(0, 0, 0, 0.15);
 }
 
 .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabs-container:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 #TabsToolbar
   .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox {
-	background: url("newtab-shadow.png") repeat-x bottom !important;
+  .tabs-newtab-button {
+	-moz-box-shadow: 0 0.3em 0.2em rgba(0, 0, 0, 0.15);
+	box-shadow: 0 0.3em 0.2em rgba(0, 0, 0, 0.15);
 }
 
 /* hide new tab button by Tab Mix Plus
@@ -31,64 +32,55 @@
 .tabbrowser-tabs[newTabButton="false"][treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabs-container:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 #TabsToolbar
   .tabbrowser-tabs[newTabButton="false"][treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 /* hide new tab button by Tab Mix Lite
 	https://addons.mozilla.org/firefox/addon/12444 */
 .tabbrowser-tabs[newTabButton="none"][treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabs-container:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 #TabsToolbar
   .tabbrowser-tabs[newTabButton="none"][treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 /* hide new tab button by Tabberwocky
 	https://addons.mozilla.org/firefox/addon/14439 */
 tabbrowser[tabberwocky-hidenewtabbutton="true"]
   .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabs-container:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 #TabsToolbar[tabberwocky-hidenewtabbutton="true"] /* not implemented on 1.1, so this is just a random guess... */
   .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 /* hide new tab button by Tab Utilities
 	https://addons.mozilla.org/firefox/addon/59961 */
 .tabbrowser-tabs[newbutton="none"][treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabs-container:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 #TabsToolbar
   .tabbrowser-tabs[newbutton="none"][treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 /* hide new tab button by others */
 :root[treestyletab-hide-newtab-button="true"]
   .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
   .tabs-container:not([overflow="true"])
   .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox,
+  .tabs-newtab-button,
 :root[treestyletab-hide-newtab-button="true"]
   #TabsToolbar
-  .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
-  .tabbrowser-arrowscrollbox
-  .scrollbox-innerbox {
-	background-image: none !important;
-}
-
-.tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]
-  .tabs-container:not([overflow="true"])
-  .tabbrowser-arrowscrollbox .tabs-newtab-button,
-#TabsToolbar
   .tabbrowser-tabs[treestyletab-style~="square"][treestyletab-style~="shadow"][treestyletab-mode="vertical"]:not([overflow="true"])
   .tabbrowser-arrowscrollbox
   .tabs-newtab-button {
-	margin-bottom: 5px !important;
+	-moz-box-shadow: none;
+	box-shadow: none;
 }