Redo All is to abandon all previous undos. After many undos if you want to cancel all that undos then simply execute Redo All command. To run Redo All click on the Redo All command under the Game menu or click on the Redo All button on the toolbar. When you install this toolbar button won't be visible because by default it is invisible.
If you want you can make it visible from the customize toolbar window under the customize menu. You can also execute Redo all from keyboard with Control+V. When you run a Redo All command game engine cancels undos one by one and finally reach the latest position achieved so far in the game. Redo All is actually a series of Redos. so game engine executes many redos and finally reach the maximum limit and finishes the redo all command. when it is over the redo and redo all commands get disabled automatically.
Redo All option will be enabled only if there is an undo possible i.e. last command was an undo. This command will be disabled if the game pointer is in the latest position or a replay is running or there is no game in the play window.
Using commands like undo, redo, undo all and redo all will considerably reduce your score because it moves the game pointer backward and forward and at the same time your game clock is running forward. So if you spend much time in undos and redos then it will increase your game time and affect overall score. So use this commands only if necessary.
To control the Redo All Speed go to the Animation Window under the customize menu and adjust the Undo All/Redo All Card Speed scrollbar and check it in the game area to see the changes. Try with different card speeds and set it to an optimal value.