Fixed issue with collapsing the panel. Fixes ticket #1015.

diff --git a/Frame.lua b/Frame.lua
index b3b8309..493ffac 100644
--- a/Frame.lua
+++ b/Frame.lua
@@ -1920,7 +1920,7 @@ do

 			-- Hide the category buttons
 			for category in pairs(MainPanel.filter_menu) do
-				if category ~= 0 and category ~= "texture" then
+				if VALID_CATEGORY[category] then
 					MainPanel["menu_toggle_" .. category]:Hide()
 				end
 			end