I would like to divide my Qt project into several directories because it is growing pretty large. However, when I click on browse in QtCreator, there is no 'Add directory' and no such thing in 'Add new'. Can this be done somehow?
One method you could use is to add a project include file for each sub directory.
Qt Creator displays these in the GUI in a nested fashion, and allows you to add files to them.
e.g.
in project.pro
include(folder1/include.pri)
in folder1/include.pri
HEADERS += MyClass.h
SOURCES += MyClass.cpp
etc