KDbg

KDbg is a graphical tool for debuggin your programs

Features

Source code, breakpoint, local variables, watched expressions, and the thread list

• Easy inspection of variables
• Basic commands (step, next, etc..) bound to function keys
• Conditional breakpoints
• A full set of tools for viewing code, searching text, and for manipulating variables.

The project home page gives more details.
A User Manual is on-line