I'm presently working on the pset3 sort and search functions and I've found that the debugger button is missing from the menu bar, the viewer is still on the right, but my ability to place breakpoints is gone. Any body know how to correct the issue?
EDIT September '16 The latest version of the IDE (69-ish) has a new utility called debug50.
I can't find a way to get the button back, but you can run the GUI debugger this way:
Less Comfortable. That will give more options in menu bar, specifically a Run tab and the green "> Run" button. When I tried the green Run, it did in fact invoke the debugger. You may need to experiment with "Run Configurations" (also in the Run dropdown), or the options in the "Run" window: