There is a toolbar along to the top of the game window that allows you to perform certain actions quickly without fumbling through menus.
Here is a detailed description of the toolbar buttons.
1. New Game Button. You can start a new game at any time by hitting the "New Game" button.
You also start a new game by selecting the "Game->Deal" option from the menu bar or by hitting the "F2" key. Click here for more detailed information about starting new games.
2. Undoing. Arachnid keeps a record of the last 1,000 moves. If you decide that you have made a mistake, you can undo one or more moves by hitting the "Undo" button on the tool bar or by selecting "Move->Undo" from the menu bar. You can also press Control-Z to undo the last move.