Keys for dialog boxes

TAB
Move to the next option or option group
SHIFT+TAB
Move to the previous option or option group
CTRL+TAB
Switch to the next tab in a dialog box 
CTRL+SHIFT+TAB
Switch to the previous tab in a dialog box 
Arrow keys
Move between options in an open drop-down list, or between options in a group of options
SPACEBAR
Perform the action assigned to the selected button; check or clear the selected check box
First letter of an option in a drop-down list
Open the list if it is closed and move to that option in the list
ALT+ the letter underlined in an option
Select an option; select or clear a check box
ALT+DOWN ARROW
Open a selected drop-down list
ESC
Close a selected drop-down list; cancel a command and close a dialog box
ENTER
Perform the action assigned to a default button in a dialog box