The Data Display Debugger (DDD) is a Motif user interface to GDB and DBX.  DDD
provides a graphical data display in which data structures are displayed as
graphs. A simple mouse click dereferences pointers or views structure contents.
Sources are available via FTP from
ftp://ftp.x.org/contrib/utilities/ddd-1.4d.tar.gz [4/96]; binaries (Sun, Linux,
and others) are available from
ftp://ftp.ips.cs.tu-bs.de/pub/local/softech/ddd/bin/ . See also
http://www.cs.tu-bs.de/softech/ddd/ for reference information.

Cygnus Support puts out GDBtk, which is a tcl/tk based interface that is
compiled into GDB. GDBtk 4.15.1 is available from ftp.cygnus.com, as
pub/gdbtk/gdbtk-4.15.1.tar.gz. [4/96]

UPS is a source-level debugger which runs under the X11 (and SunView) window
systems on Sun, DEC, and Linux platforms. It is available from
ftp://ftp.x.org/contrib/devel_tools/ups-2.45.2.tar.Z , along with several
binaries. Also in that archive is a 3.14 beta and a 3.7 alpha [7/95].  Rod
Armstrong (rod@san-jose.ate.slb.com) has made some unofficial enhancements;
they are at ftp://ftp.x.org/contrib/devel_tools/ups-2.54-RGA.README and
ftp://ftp.x.org/contrib/devel_tools/ups-2.54-RGA.tar.gz .

xdbx, an X interface to the dbx debugger, is available via ftp from
ftp://ftp.x.org/R5contrib/ . The current and apparently final
version [1/91] is 2.1 patchlevel 2.

An X interface to gdb called xxgdb is similar to xdbx 2.1.2.  
Sources are on ftp://ftp.x.org/R5contrib/ [3/96].

mxgdb is a Motif interface to gdb by Jim Tsillas (jtsillas@proteon.com);
version 1.2.1 is on ftp://ftp.x.org/contrib/devel_tools/mxgdb-1.2.1.tar.gz
[3/96].

Also:

Certain vendors (MIPS, Sun, SCO) ship X-based debuggers. Sun's SPARCworks is
an integrated development environment.

CenterLine's CodeCenter (617-498-3000) source-level debugger, available on most
major platforms, includes an X-based interface.

The PDB debugger is part of the OI distribution.

The Energize Programming System developed by Lucid and now sold by Tartan
is a tightly-integrated development
environment for C and C++ programs. Energize incorporates a graphical user interface
on top of an extended version of gdb. Info: tnt-support@tartan.com,
+1 412-856-3600.