This may be a dumb question, I realize, but this is quite frustrating for me right now so I’m going to ask anyway.
I’m following the C/C++ Development User Guide in the Eclipse help.
I’m at C/C++ Development User Guide -> Getting Started -> Debugging projects
At this point I am told the following:
In the Variables view, right-click the input variable, and select Change Value... and type 'm' between the single quotes and hit OK.
Except, there is no Change Value...! Here is a screenshot of what it looks like for me:

Where is Change Value...? Whiskey Tango Foxtrot?!
Ok I figured things out after much pain.
I had installed the gdb provided by XCode 3:
GNU gdb 6.3.50-20050815 (Apple version gdb-1515) (Sat Jan 15 08:33:48 UTC 2011)There appears to be better compatibility with Eclipse and Photran, and perhaps with whatever version of the GCC I was using.
The solution to my problem came about by installing the fink
gdbpackage, which is GDB 7.1.Note that this is called with
fsf-gdbto avoid a conflict with the Apple Dev Tools GDB.Thus, you’re going to need to change your debug configuration in eclipse to point to
fsf-gdbfromgdb.May this help any other poor souls who happen to want to debug with Photran on a mac.