Default Path/File Mode

I want to have a way to open CtrlP always in same mode. The problem is that once you toggled it using **C-D**, the next time you open CtrlP, it will have the last used mode.
There is **g:ctrlp_by_filename** option, but this one is used only first time. Maybe we can just use the option **g:ctrlp_by_filename** on every invocation of the Open function?
