One form of problem I commonly encounter is that DraftSight under MacOS 10.6.8 appears to hang, with most of the menu items missing.  Only the DraftSight menu item survives, but the Quit DraftSight item is grayed out, and so does not work.  While one can usually regain control using Force Quit, I find that Escape (Esc) often works as well, recovering control without losing unsaved work.