Hi,
I have spend several hours trying to fix the non working "deadlock keys" and "accents" on PlayOnLinux. To fix it:
-Click on "Configure"
-Select the application with "deadlock keys" or "accents" problems
-Select "Miscellaneous" tab
-Write the next text at "Command to exec before running the program":
XMODIFIERS=''
-Close the "Configure" window and run the application
I hope this helps someone.
(Some other forums suggest changing the "locale" but it is difficult and does not really work, other posts suggest changing the wine version to "Windows 7" but it breaks some application dialogs)