OK, I have addressed the problem. The reason of this phenomenon is because of the lack of auto-left-side aligned function on toolbar.
After I switch on the 'Code completion' which is totally non-used function for me, the originally exist two bars ---- debuger and compiler are all pushed to the right side of toolbar. However, after I switch off the 'Code Completion' , the 'Debugger and Compiler' bars do not auto aligned to the left side of toolbar, they remain at the old position which is outside of the screen. So that I can not see them on screen.
