Message 56876 - Python tracker

This (relatively speaking) simple patch allows the full doc-string of a
callable to be displayed in a textView window. Once a call-tip is being
displayed, hitting one of the keys which is bound to the
force-open-calltip virtual event (Control-backslash by default) opens
the new window. If there is no extra documentation to be shown (in
addition to what is already shown in the call-tip), the window is not
displayed.