If you want an easy way to change worlds with the click of a button then bookmarks if the way to go when hopping worlds.
You can load both HD and LD worlds from the lists
How To Use
1. Open Firefox
2. Click "Bookmarks" at the top of your screen.
3. Click "Organize Bookmarks..." in the menu you opened in step 2.
4. Click "Import and Export" and hit "import".
5. Select the Bookmark file you downloaded and hit open.
6. Now in your Bookmarks menu a worlds list should be there.