The View my changes action is available in the shortcut menu of a locked (for editing) document.
Note
This is not available for OpenOffice.org documents.
It will compare the [in development] revision of the selected document with the [current] revision thus showing the changes made by the user who locked the document. This action is only available for the user who locked the document.
Refer to Compare Document Revisions for a remark on protected documents.