diff --git a/content/treestyletab/treestyletabbrowser.js b/content/treestyletab/treestyletabbrowser.js
index 943f4d66..1cb32053 100644
--- a/content/treestyletab/treestyletabbrowser.js
+++ b/content/treestyletab/treestyletabbrowser.js
@@ -2978,7 +2978,7 @@ TreeStyleTabBrowser.prototype = {
 			else
 				x += this.splitterWidth;
 			w -= offset;
-		}
+		}
 		ctx.globalAlpha = 1;
 		if (pos == 'left' || pos == 'right') {
 			ctx.fillStyle = this.splitterBorderColor;
@@ -2986,14 +2986,21 @@ TreeStyleTabBrowser.prototype = {
 		}
 		ctx.save();
 		ctx.scale(zoom, zoom);
-		ctx.drawWindow(frame, x+frame.scrollX, y+frame.scrollY, w / zoom, h / zoom, '-moz-field');
+		ctx.drawWindow(
+			frame,
+			(x / zoom)+frame.scrollX,
+			(y / zoom)+frame.scrollY,
+			w / zoom,
+			h / zoom,
+			'-moz-field'
+		);
 		ctx.restore();
-		if (this.mTabBrowser.getAttribute(this.kTRANSPARENT) != this.kTRANSPARENT_STYLE[this.kTRANSPARENT_FULL]) {
-			var alpha = Number(this.getTreePref('tabbar.transparent.partialTransparency'));
+		if (this.mTabBrowser.getAttribute(this.kTRANSPARENT) != this.kTRANSPARENT_STYLE[this.kTRANSPARENT_FULL]) {
+			var alpha = Number(this.getTreePref('tabbar.transparent.partialTransparency'));
 			if (isNaN(alpha)) alpha = 0.25;
 			ctx.globalAlpha = alpha;
-			ctx.fillStyle = 'black';
-			ctx.fillRect(0, 0, w, h);
+			ctx.fillStyle = 'black';
+			ctx.fillRect(0, 0, w, h);
 		}
 		ctx.restore();
 	},