Lock and unlock files and folders
Though Subversion integration allows you to successfully modify and merge files changed by different team members, sometimes it makes sense to lock files (for example, images) to avoid overwriting changes.
Lock a file
Select the file you want to lock in the Project tool window or open it in the editor.
Select VCS | Subversion | Lock from the main menu, or Subversion | Lock from the context menu of the selection.
Enter a lock comment in the Lock File dialog that opens.
Unlock a file
Select the file you want to unlock, or open it in the editor.
Select VCS | Subversion | Unlock from the main menu, or Subversion | Unlock from the context menu of the selection.
To forcibly break a lock set by somebody else, select the Steal Existing Lock checkbox.
Apart from locking files and folders, you can toggle their read-only attribute by using the 
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status bar icons or the , or main menu commands. For more information, refer to Toggle read-only attribute of a file.