The accessibility bridge code that exports accessible objects on the bus is now used by default; atk-bridge has been converted into a library that CTK+ links against. To void the linking, pass --without-atk-bridge when configuring CTK+.

CDK threading support has been deprecated. It is recommended to use g_idle_add(), g_main_context_invoke() and similar funtions to make all CTK+ calls from the main thread.

CTK+ now follows the XDG Base Directory specification for user configuration and data files. In detail,

Existing files from the old location will still be read if the new location does not exist.

$HOME/.ctk-3.0 is no longer in the default module load path. If you want to load modules from there, add it to the CTK_PATH environment variable.