While editing source code in the editor, you can select a function name and press F3, and the editor immediately jumps to the prototype for that function (if the file is also in your project). Or, you can also press CTRL and Click to navigate to the prototype. Additionally, you can navigate to files (such as headers) outside of the workspace (i.e. in the QNX target directories).
Press Ctrl F3, and the editor immediately jumps to the function's implementation (if the file is also in your project).