The contents of the selection as a UTF-8 encoded string, or null if an error occurred.
Errors: Possible errors include @ref GLFW_NOT_INITIALIZED and @ref GLFW_PLATFORM_ERROR.
The returned string is allocated and freed by GLFW. You should not free it yourself. It is valid until the next call to @ref glfwGetX11SelectionString or @ref glfwSetX11SelectionString, or until the library is terminated.
This function must only be called from the main thread.
@sa @ref clipboard @sa glfwSetX11SelectionString @sa glfwGetClipboardString
Added in version 3.3.
Ingroup: native
Returns the contents of the current primary selection as a string.
If the selection is empty or if its contents cannot be converted, null is returned and a @ref GLFW_FORMAT_UNAVAILABLE error is generated.