The project aims to provide a stragihtforward means to build graphical user-interfaces in Fortran based on Tcl/Tk. In its current state it is proof of concept, not a full-fledged library. While only some basic features have been implemented, it does show the possibilities of leveraging Tcl/Tk for this purpose.
The philosophy of the interface is that much can be done via evaluating Tcl commands, rather than calling the Tcl API directly. Of course, this means that some roundabout processing is required: building the string representing the command first in Fortran and then having it evaluated by Tcl/Tk. Still, for the purpose of setting up the GUI this is fast enough and it saves detailed interfacing between C and Fortran.
Another consideration of this interface is that much if not all can be done via Fortran directly, thanks to the standardised C-Fortran binding. That does mean that some things are a trifle difficult: the stubs mechanism relies on macros, just as the lifetime management for TclObj data structures and Fortran can not deal with C macros. That means that, at least for the moment, the interfacing relies on the string interface.
The library does not provide any error handling yet. It is after all a proof of concept.
The project contains a single demo program. It needs to be built as a library that can be loaded by Tcl/Tk's wish program. The sample build script demonstrates this.
A convenient aspect of simply loading a library is that the Fortran part does not need to initialise the interpreter.
The demo program does not pay much attention to the layout. That is something that needs to be improved. Also, a lot of convenience routines are still missing.