Historically CreateEx() has been thought as Create() with additional functionality like more styles.
So, if you take a look at many MFC classes which provide CreateEx() and Create(), you can see that CreateEx() calls Create() and do more chores to provide added functionality.
However, I found out that CDockablePane’s doesn’t.
Although MSDN document shows that there is CreateEx() for CDockablePane, it actually doesn’t exist.
So, you shouldn’t be fooled by the MSDN document and create CDockablePane with CreateEx() and wonder why it doesn’t work.