The Undo and Redo functions are accessible through the Edit menu from the top toolbar:

Edit > Undo
Edit > Redo

or by using the following shortcut keys:

Undo Shortcut Keys:

  • CTRL + Z on Windows, Linux
  • CMD + Z  on Mac OSX

Redo Shortcut Keys:

  • CTRL + Y on Windows, Linux
  • SHIFT + CMD + Z on Mac OSX

Actions that can be undone / redone:

  • Annotations  (Textbox, callout, sticky note, typewriter, 8 shapes, sound, image, link, area highlight, measurements, stamp)
    • Add
      • New
      • Paste
      • My Comments
      • Recent Comments
    • Move
      • Mouse
      • Keyboard
    • Resize
    • Change properties
    • Flatten
    • Delete
    • Mark with Checkmark
    • Review
  • Bookmarks
    • Add
    • Rename
    • Delete
    • Reorder
  • Content editing – text, path objects, image
    • Redact (before being applied)
    • Delete
    • Move
    • Edit text properties (text data, font, outline color, size, etc..).
    • Edit path object properties
    • Resize path and image
  • Form
    • Edit field contents
  • Markup  (highlight, crossout, underline, squiggly, replace, insert)
    • Add
    • Move
    • Change properties
    • Flatten
    • Delete
  • Pages
    • Rotate
    • Crop
    • Header/Footer/Watermark

Actions that reset the undo / redo stacks:

  • Document
    • Save
    • Security
      • Sig Field
      • Sign
      • Remove Sig
  • Page
    • Move
    • Delete
  • Form
    • Flatten form fields
    • Reset form fields

Actions that are being ignored:

  • Document
    • Attach file
    • Add a blank page
    • Insert pages
  • Import Annotations

Undo was implemented in PDF Studio 8 and improved in PDF Studio 9.