+The contructor registration to the main window adds button and menu entry
+to each main window, thus allowing instanciation of viewers.
+
+
+Main Window
+
+The main window is a container that offers menus, buttons and a notebook. Some
+of those menus and buttons are part of the core of the main window, others
+are dynamically added and removed when modules are loaded/unloaded.
+
+The notebook contains as much tabs as wanted. Each tab is linked with a
+set of traces (traceset). Each trace contains many tracefiles (one per cpu).
+A trace corresponds to a kernel being traced. A traceset corresponds to
+many traces read together. The time span of a traceset goes from the
+earliest start of all the traces to the latest end of all the traces.
+
+Inside each tab are added the viewers. When they interact with the main
+window through the lttvwindow API, they affect the other viewers located
+in the same tab as they are.
+
+The insertion of many viewers in a tab permits a quick look at all the
+information wanted in a glance. The main window does merge the read requests
+from all the viewers in the same tab in a way that every viewer will get exactly
+the events it asked for, while the event reading loop and state update are
+shared. It improves performance of events delivery to the viewers.
+
+