These come in handy if you’ve got to use this app.
keyboard shortcuts for Microsoft Project:
Hide subtasks ALT+SHIFT+HYPHEN or
ALT+SHIFT+MINUS SIGN (minus sign on the numeric keypad)
Indent ALT+SHIFT+RIGHT ARROW
Show subtasks ALT+SHIFT+ = or
ALT+SHIFT+PLUS SIGN (plus sign on the numeric keypad)
Show all tasks ALT+SHIFT+* (asterisk on the numeric keypad)
Outdent ALT+SHIFT+LEFT ARROW