Use Modify|Fix to fix (or 'repair') the selected directory/files. This option is only applicable for certain, unusual working copy states:
SVN repositories and working copies are in general case-sensitive. This can cause problems when working on a case-insensitive operating system, like Microsoft Windows or certain file systems on Apple Mac OS, and changing the file name's case (upper-case to lower-case, etc.). Because of SVN's working copy format and the pristine copies, it's technically not possible to handle such a file name case change.
One solution is to avoid this situation by either only performing file name case changes on an operating system which supports case-sensitive file names, or directly in the repository by using the Repository Browser.
At any rate, a file name case change may happen on a case-insensitive operating system, e.g. because of defect software tools, etc. SmartSVN detects such invalid changes and puts the file into case-changed file state, see Rare Primary File States. Fix will now change back the file name case to its original form as found within the pristine copy, resolving this problem.
A nested root (see Primary Directory States) is a working copy within another working copy which is not related to this parent working copy. SVN commands ignore such nested roots; they are simply treated as unversioned directories.
Nested roots typically result from moving a directory from one location to another without using the proper SVN commands, like Move. This leaves a missing directory at its original location and introduces a nested root at its current location.
Fix offers the following solutions for nested roots, depending on their origin:
If a directory has been scheduled for addition (see Add) and has been locally deleted afterwards (i.e. the directory and its containing SVN admin area .svn is missing), the directory is in Added-missing state (see Primary Directory States).
Such directories are actually only a leftover entry in the parent directory's SVN admin area. The resolution is to Revert them, which is what this command will do.